While you may be au fait with the USA's best-known attractions, those willing to walk on the weirder side will be rewarded. From bizarre museums to curious landmarks, America has no shortage of oddities.

Read on as we reveal our favourite wacky sights in America's biggest cities...

Those passing under Seattle’s George Washington Memorial Bridge are in for a fright. A grave-faced troll lurks beneath the overpass, fingers dug into the dirt – one of the monsters’ eyes is covered by a lop of hair, the other peers ominously at passersby. The feat was completed in 1990 by a team of four artists: Donna Walter, Ross Whitehead, Will Martin and Steve Badanes.

You’d be forgiven for walking straight past this tiny museum in Lower Manhattan. Crammed into an abandoned freight elevator, Mmuseumm makes a show of the everyday, taking seemingly banal objects (think soda bottles, hairbrushes and action figures) and forcing visitors to examine them afresh. Collections include the Wall of Globalization, a gathering of items “indispensable to our daily life”, featuring underpants, crisp packets and a selection of newspapers.

Flattened to the walls, hanging from the porch, decorating the front gate – beer cans, more than 50,000 in total, cover this Houston house. It’s the vision of John Milkovisch, who began bedecking his family home with beer cans back in the 1960s. Though he abhorred waste, straight-talking, beer-loving Milkovisch insisted that his work was for no greater purpose than simple enjoyment. Now, both Milkovisch and his wife have passed away but the house is open for ticketed tours on weekends.

Named after the neighbourhood you’ll spot them in, these otherworldly structures are the work of late Italian-immigrant artist Simon Rodia, who bought the site they stand on in 1921. Rodia built the towers single-handedly, festooning them with found materials such as sea shells and glass. He originally christened the site Nuestro Pueblo, meaning 'our town'. Rodia’s motivation remains unclear but the towers are impressive nonetheless, the tallest spiralling to 99.5 feet (30.3m).

A mysterious riverfront site, the Miami Circle got archaeologists excited when they discovered the area in the late 1990s. Though they're unable to pinpoint their exact origins, experts say that the basins and holes whittled into the limestone here indicate prehistoric activity. Artefacts, such as tools and ceramics, thought to belong to ancient settlers were also discovered. Miami Circle has been a National Historic Landmark since 2009.

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An open-air gallery, the Magic Gardens is a labyrinth of mosaic passageways created by Philadelphia artist Isaiah Zagar. The first mirrored tile was placed back in 1991, a stone’s throw from Zagar’s studio. Today, the installation stretches around half a block.

The bright lights of Sin City still shine at this unique 'cemetery'. Part of the Neon Museum, the Neon Boneyard is a resting place for some of Vegas’ retired signs. Once glittering atop hotels and restaurants, around 250 signs are now heaped together higgledy-piggledy, their glory days behind them. The signs date back to the 1930s and include those from the New York-New York hotel and the now-demolished Stardust Resort and Casino.

The Golden City has a lauded live music scene and here even Mother Nature is a musician. The Wave Organ was built on the San Francisco Bay in 1986, pioneered by artist Peter Richards and realised with the help of sculptor George Gonzalez. The instrument sits on a jetty carved from granite and marble and, as water moves in and out of the 25 organ pipes, an ethereal song plays. The clearest sound is produced at high tide.

It's been almost 20 years since pocket-sized ponies began popping up across Portland. The project started as a way to showcase the mysterious metal rings found around the city – in fact, these rings were once used to tie up carts pulled by real horses as their masters went about town. The installation idea came from artist Scott Wayne Indiana who, inspired by times gone by, began tethering toy steeds to these loops – now people all over Portland have participated.

A unique botanical garden, this site earned its name since it’s some 10 feet (3m) below sea level. A surprising find in the city, this tropical bolthole sells itself as a ‘living museum’, with some of the plants more than a century old. Bird lovers should be on the lookout for the flock of Chilean flamingos parading about the park.

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The city of Homestead, near Miami, seems an unlikely setting for a collection of eccentric limestone sculptures. Carved by Ed Leedskalnin, who was jilted the day before his wedding, the artworks are a testimony to Ed's former fiancee and lost love, built over a period of 28 years from 1923 to 1951. Coral Castle Museum is open to visitors.

'Art too bad to be ignored' is the slogan of this offbeat gallery. Touting itself as the only institution of its kind, the museum showcases lumpy life drawings, unconventional portraits and cartoonish landscapes, ranging from the slightly amateurish to the downright bizarre. It’s celebratory rather than scathing, rejoicing in the 'special quality' of each work. 

This curious ‘castle’ in Phoenix looks about ready to tumble but it’s built on firm foundations. It was constructed by Seattle native Boyce Luther Gulley in the late 1920s after he was diagnosed with tuberculosis. Upon learning of his likely terminal prognosis, he envisioned building his daughter the castle of her childhood dreams, and set about doing so with rocks and other scrap materials. Indeed, Gulley’s daughter Mary Lou lived here until her death in 2010. The castle is currently closed due to storm damage and vandalism, but keep your eyes peeled for its reopening.

Usually trodden into sidewalks or moulded under window sills, chewed gum isn't often a welcome addition to a city’s streets. But Seattle found a way to harness the sticky stuff's artistic potential. The kaleidoscopic gum wall has been here since the 1990s – it stretches for more than 50 feet (15m) and is regularly topped up by Seattle’s gum-chewing crowds. It’s gross, yes, but it’s really quite beautiful too.

This Irish bar boasts some unusual punters. Silky O’Sullivan’s has a ‘goat tower’: a wooden structure designed specially for its resident billy goats' enjoyment. The bar was opened in 1992 by the late Thomas 'Silky' Sullivan. His inspiration to keep goats came from Ireland’s annual Puck Fair, which historically sees a wild goat captured and crowned 'King Puck' for the event’s duration. It’s returned to the wild after the festivities. Beyond this, the bar has the usual trappings: darkened booths, shamrock motifs and free-flowing Guinness.

This quirky arts space in DC, previously named Blind Whino, certainly turns heads. Covered with eye-popping murals in hot pink, green and blue on the outside, it’s dedicated to the work of mostly local artists inside. The space was converted from the 1886 Friendship Baptist Church, and the Romanesque and Victorian architectural features – arched windows and decorative carvings – still peep from behind the paint.

One of the world’s largest museums dedicated to anatomical curiosities, Mutter Museum says its purpose is to help visitors 'understand the mysteries and beauty of the human body'. Many displays painstakingly chronicle medical advancements, such as the approach to spinal surgery, while others include pieces of Einstein’s brain (pictured) and a collection of 139 human skulls obtained from Viennese anatomist Josef Hyrtl.

One man’s trash is another man’s treasure, so they say – and that’s certainly the mantra of Vince Hannemann, Austin’s 'junk king'. His Cathedral of Junk was born in 1988, and is exactly what it sounds like – an eccentric shrine to trash in all its forms, built up in the artist’s backyard. Hannemann continually adds to his trash tribute and it now towers more than 33 feet (10m). Visitors must call ahead and make an appointment to visit.

A passion project by San Diego couple Edna and Alex Harper, these fascinating gardens were born in the duo’s front yard. Twenty years later, some 50+ caricatures have been shaped from their property’s lush foliage, with figures including a whale and a mighty dinosaur.

Melodies catch on the breeze in the Big Easy’s City Park. Close to the park’s Big Lake, you’ll find a sprawling old oak tree whose branches are trimmed with a series of wind chimes, one of which is 14-feet (4.2m) long. New Orleans sculptor Jim Hart was behind the concept and visitors can sit beneath the tree, enjoying the gentle music as the wind tickles out a tune.

This sculpture was built by Japanese-American artist Isamu Noguchi to harness a rare solar event. Situated by the city’s Municipal Building, the structure itself is simple: an undulating hunk of grey steel atop three giant legs. Usually its bendy frame casts a wobbly shadow. But, twice a year, Hawaii experiences a phenomena called the Lahaina Noon – at this time, the sun passes directly overhead this very spot and the sculpture’s shadow forms a perfect circle on the concrete disc beneath it.

Wildly-decorated vehicles are the forte of this kooky Houston art museum. Spearheaded by Texan artists Ann and James Harithas, the museum opened in 1998 and now also showcases fine art, sculpture, photography and more. The cars steal the show, though, and you’ll find them decorated with delicate leaf patterns, lined with colourful beads and even strung with fairy lights.

These guys have pizza on the brain indeed. They’re a restaurant primarily, famed for their innovative toppings (think dried cranberries, peanut sauce, and hot dogs and mustard). But they also lay claim to the largest collection of pizza memorabilia in the world – posters, arcade games, video exhibits and more make up the world’s first pizza museum.

This eclectic work of outsider art takes up almost a full block on Detroit’s East Side. Enigmatic artist Tyree Guyton, who grew up here, can be seen pottering around the site, tinkering with his weird and wonderful structures made from all manner of objects: chairs, clocks, stuffed toys, shoes. Even the houses haven’t escaped Guyton’s touch, emblazoned with bright patterns or strung with items he’s found about the city.

Albuquerque’s tumbleweed 'snowman' has become something of a tradition. While this desert city does occasionally get snow, prickly tumbleweed is all the more ubiquitous and the folks at the city’s Flood Control Authority (AMAFCA) put the stuff to good use. Shortly after Thanksgiving, the organisation erects the 'snowman' beside one of the city’s biggest freeways, typically smartened up with a jolly red bow tie and a blue AMAFCA-branded hat.

If you’re wandering around Atlanta, keep your eyes towards the floor. Peppered around the city are pint-sized doors installed by Atlanta-based artist Karen Anderson. You’ll find them in tunnels, beside stores, in skate parks, at the aquarium and beyond. Each one is unique: one boasts a dog flap, another is surrounded by mural butterflies, some are hemmed by rainbows. According to Anderson, there’s no reason for the doors other than public enjoyment and a celebration of the city.

This vivid example of public art began life in 1995 when eccentric artist Randy Gilson started painting murals on the house he’d just bought. Today the facade of the three-storey property is a riot of colour – bright yellow, cornflower blue and hot pink – and sculptures spill from the garden.

One man’s love of oranges inspired this tribute to the fruit. With the air of a niche funfair, the architectural site is full of winding mosaic walkways opening out onto bizarre arena-like spaces. It covers some 3,000 square feet (279sqm) and is dotted with a small pond, a stage and a museum. The late Jeff McKissack, a postal worker in the city, was the orange-lover behind this wacky monument. He built it entirely by hand using a mix of regular building materials and a slew of found objects.

This crooked spot is certainly mysterious. Tucked in Santa Cruz’s surrounding redwood forest, this area is touted as a gravitational anomaly. The focus is a tilted cabin, reached by hiking a zig-zagging trail. Once inside, visitors report strange gravitational pulls and the ability to walk up walls. Though the Mystery Spot makes pains to keep up its gravity-defying illusion, most experts agree it’s a trick – the impression of flouting gravity is created by the angle of the cabin.

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This larger-than-life pew is for peering at rather than perching on. You’ll find it in DC’s Anacostia neighbourhood, towering at almost 20 feet (6m). It was the world’s largest chair when it was built in 1959. At the time it was a marketing ploy for Curtis Brown’s Furniture company and today, the aluminium replica of the landmark remains a symbol of commercial success and industry.

In Battery Park, in Manhattan, there are angelfish, triggerfish and butterflyfish. Yet these marine creatures aren't in the waters of the New York Harbor but part of a stunning carousel made from fibreglass. Unlike a typical fairground ride there's no central pole as the carousel's electric motors are housed below the floor.

WonderWorks turns the concept of a children’s museum on its head – literally. The sizeable white building is roof to the ground, foundations in the air, with spidery cracks across its facade and crumbling columns completing the illusion. Inside, the focus is on 'edu-tainment' with interactive exhibits exploring natural history, physics, art and more. 

An eerie route running through Constitution Lakes urban park in Atlanta, the Doll’s Head Trail is exactly as it sounds. The severed heads of cherub-faced dolls and other toys found around the park have been used to mark out a track, forming a peculiar type of hiking trail. You’ll loop through woodland, past lakes and over boardwalk-covered wetlands, with chubby dolls’ arms pointing you in the right direction should you swerve off the path. 

Take a look at these places you won't believe are in the USA

Located in the centre of Memphis' Memorial Park Cemetery, this bizarre man-made cave depicts scenes from The Bible using crystals,  concrete sculptures and lighting effects. The work of Mexican artist Dionicio Rodriguez back in the 1930s, Crystal Shrine Grotto has become an unlikely tourist attraction, drawing in around 100,000 visitors a year. Colourful and spiritual, the 60-foot-deep (18m) cave features almost five tonnes of raw crystals, collected from the Ozark Mountains in Arkansas, that surround the religious figurines.

If you're wandering by the Whitehall Corporate Center in Charlotte and get the feeling you're being watched, you probably are. A huge 25-foot-high (7.6m) glistening head, made up of 40 rotating stainless steel plates, stares at passers-by. Created by renowned Czech sculptor David Cerny, Metalmorphosis is lovingly described as 'one of the seven wonders of Charlotte' by locals and has remained a striking part of the cityscape since 2007.

You could be forgiven for thinking you're hallucinating when driving past this office building in downtown Milwaukee. But since 1999, three giant ladybirds (or ladybugs) have been crawling down the exterior of the property formally known as Milwaukee Building. The six-foot-tall (2m) fibreglass bugs were commissioned by property owner John J Burke, who just "thought they were cool", according to his daughter Wendy. If you pass by at night, you'll see them lit up in all their glory.

This seasonal attraction has been making Indianapolis locals and tourists smile every winter since 1961. Creating the ice tree became a hobby for the Veal family after realising the spray of water off a nearby pond blew onto honeysuckle bushes and created an icy spectacle one harsh winter's night. It has been purposely made every year since when temperatures drop to -6°C (20°F) for at least five consecutive days, usually in January. The colours are created using food colouring sprayed onto the ice.