No matter what's going on at the moment, the world is peppered with mysterious and intriguing ancient sites and lost citadels. There are plenty of places that are still very much functional cities, but have been inhabited for centuries, if not thousands of years. From obvious cradles of modern civilisation to captivating cities in the New World, join us on an armchair tour around some of the most historic cities on Earth and discover the fascinating stories they hold.

Once an ancient Egyptian city called Thebes ruled by powerful pharaohs, including Tutankhamun (1334–1325 BC), the city was the most venerated of ancient Egypt in its heyday. Today, known by its modern name Luxor, the Nile still flows alongside the modern city and the grand temple complex that lent the city its name.

Obviously, the two most famous sites here are the Luxor Temple and the Great Temple of Amun at Karnak (pictured). The latter, still the second largest religious building ever built, is the house of worship dedicated to Amun, Thebes' patron deity and the chief deity of the Egyptian Empire. Unlike other temples in Thebes, the Luxor Temple wasn't dedicated to a deity, but rather to the Egyptian pharaohs and is thought to be the place where many of them were crowned. Discover what the Seven Wonders of the Ancient World would look like today.

Sun-kissed St Augustine has serious credentials when it comes to history. The oldest continuously inhabited European settlement in the continental United States, St Augustine was established in 1565 by Spanish explorers. Many of the Historic District's (pictured) buildings date back to the 1700s and the area is still very much the heart of the city with plenty of restaurants, shops and hotels.

The 17th-century Spanish fort Castillo de San Marcos (pictured), which commands the western shore of Matanzas Bay, represents more than 340 years of history in the area. It weathered many attacks during the colonial wars and is now a national monument. The oldest masonry fort in the continental United States, it was finished in 1695 and has been significant to the history of the US ever since. Here are more of America's most charming historic downtowns.

Chester, in the northwest of England, was founded as a Roman fort in AD 79. Known as Deva, it's the best-preserved walled city in the country, with its magnificent medieval walls almost completely encircling the historic centre. The circuit around the ancient defensive system, originally started by the Romans, stretches for two miles (3.2km). Other Roman remains include the vast amphitheatre, which is Britain's largest, and the Roman gardens.

Aside from its Roman legacy, the pretty city is also home to the 12th-century Agricola Tower (pictured). It was once a gateway to Chester Castle, which was founded by William the Conqueror in 1070. Chester is also famous for the Rows – a series of unique two-level galleried arcades that are 700 years old – and its 1,000-year-old cathedral.

Varanasi, nestled on the banks of the river Ganges, is regarded as the spiritual capital of India and its diverse cultural and religious history is palpable. According to Hindu mythology, Varanasi was founded by one of the three principal deities, Shiva. It's also believed to be the place where Buddha founded Buddhism around 528 BC and during the Middle Ages it was a centre for intellectuals and theologians.

With some 2,000 temples, the city usually attracts a large number of pilgrims as well as those coming to perform funeral rites in the river Ganges' sacred waters. One of Varanasi's most unique sights are the ghats – the embankments made in steps of stone slabs for pilgrims to perform the rituals. The city is said to have around 84 ghats, some privately owned. The Dashashwamedh Ghat is probably the oldest and is believed to have been built by Brahma (a creator god in Hinduism) to welcome Shiva. 

There are a few contenders for the title of Europe’s oldest city, but the proud citizens of Cádiz insist that their striking Atlantic oasis is the real deal. And it seems archaeologists have confirmed it too as walls dating from the 8th century BC have been found deep underneath the Old City within the last 10 years. It’s certainly the oldest continually inhabited city in Spain and one of the most beguiling too.

Within the city's historic streets, it’s easy to imagine the Phoenicians parading around three millennia ago and the Moors holding sway as they spread their power throughout southern Spain and beyond, and whose influences very much pervade the city today. The winding, narrow lanes of Old City are a stark contrast to the wide avenues of newer areas as are modern glass buildings in comparison to the historic, often worse-for-wear structures. Here are more of the world's most underrated historic small cities.

China is home to one of the world’s oldest civilisations and is rich in extraordinary and ancient treasures. Perhaps none more so than the entire army of terracotta warriors and horses (pictured) that were buried with First Emperor of China Qin Shi Huang for more than 2,000 years before their excavation. The incredibly life-like army now reside at a museum which was built around the excavation site near Xi'an in central China.

The city itself is of great historic significance too. Today, the capital of Shaanxi Province, it's one of China's oldest cities and one of the Four Great Ancient Capitals alongside Beijing, Nanjing and Luoyang. Its importance throughout history has been great not only as the seat of many powerful Chinese dynasties, but also as the starting point of the Silk Road. The city is filled with incredible historic monuments that have survived to today, including the Giant Wild Goose Pagoda, which is more than 1,000 years old, and the city's historic walls (pictured).

While this enticing city in central Vietnam isn't among the world's oldest, it certainly is among the most interesting. The capital of Dang Trong Kingdom in the 18th century and the Nguyen Dynasty between 1802 and 1945, Hue's history stretches as far back as the 4th century, when Hue belonged to the ancient Kingdom of Lâm Ap. However, it's the city's imperial past that continues to intrigue.

Hue's famous Imperial City (pictured) is a vast 19th-century citadel surrounded by a moat and stone walls. Inside, it includes the palaces and shrines, the emperor's home and a replica of the Royal Theatre. More recent history is encapsulated within the Imperial City's walls as well as several bullet holes from the military conflicts of the 20th century, including the Vietnam War, can still be seen. Take a look at 50 photos of amazing worldwide wonders we've just discovered.

With a rich pre- and post-Colombian history, Quito is often regarded among the most significant historic cities of South America and is possibly the continent's oldest continuously inhabited city too. While its origins date back to 2,000 BC, it was settled in AD 980 by the Quitu tribe, who lived in the area before the European arrival. Colonised by the Spanish in 1534, the city's historic centre is one of the largest, least altered and best-preserved in the Americas.

The historic centre has about 130 monumental buildings and 5,000 heritage properties, including the imposing Basílica del Voto Nacional. The most important and significant neo-Gothic building in Ecuador and the whole of South America, it was once the largest cathedral in the New World. Similarly, the Carondelet Palace (today the seat of the government) was built around 1570 to firmly establish the Spanish power in Ecuador, while the medieval Church of San Francisco (pictured) is the largest historic architectural ensemble in Latin America.

Philadelphia might be significantly younger than some of the other cities on this list, however, its historic importance is unquestionable. Dubbed the birthplace of a nation (the nation being the USA, of course), the city's historic district holds a concentration of some of the most significant landmarks, including the Independence Hall (pictured), where the Declaration of Independence and the Constitution were signed, and the Liberty Bell.

Philadelphia is also proud to have the oldest residential street in America – the cobble-stoned Elfreth's Alley (pictured). Once home to the fledgling city's many merchants and artisans, most of these narrow, shuttered houses remain privately owned. However, there is an enticing museum spread across two houses built in 1755 that offers a glimpse into what life was like in 18th-century Philadelphia. Take a look at 30 of the world's most beautiful and historic streets.

A city with an illustrious past, Istanbul has lived through several incarnations, first as Byzantium and then Constantinople. Founded in around 660 BC, Istanbul has served as an imperial city for almost 16 centuries. Not only a political and cultural centre, Istanbul has always been an important connection between Asia and Europe. The western end of the Silk Road, it has also controlled the rail networks between Europe and the Middle East and was the only sea route between the Black Sea and the Mediterranean.

There are several historic landmarks Istanbul is proud to have, but none is more telling of its history as the Hagia Sophia. Built in AD 537, it was the world's largest building at the time and an Eastern Orthodox cathedral until 13th century, when it was converted into a Roman Catholic cathedral. When the Ottomans conquered the then Constantinople in 1453, the cathedral was transformed into an Ottoman imperial mosque until 1935, when it was secularised and turned into a museum. Discover more fascinating stories behind the world's most beautiful cathedrals. 

Founded as a city in 1608, Québec City has many historic accolades to be proud of – it's the oldest city in Canada, the oldest French-speaking city in the Americas and one of the oldest continuously inhabited European cities in North America. The only fortified city north of Mexico whose walls still exist, Québec City's illustrious past is on show at such significant landmarks as the Citadelle of Québec, an intact fortress from the 19th century, and the gates connecting Old Québec (Vieux-Québec) with the modern areas.

Although Québec City isn't short of romantic streets, Rue du Petit-Champlain has to be the prettiest and also one of the most historic. One of the oldest commercial streets in North America, it's now a pedestrian-only boulevard located at the foot of the cliff below the Château Frontenac. Named after Samuel de Champlain, who founded Québec City in 1608, the charming street is home to boutique shops and family-owned restaurants, many of which have been there for decades. Now see Canada's most adorable small towns and villages.

Peru is packed with age-old Inca sites, but only a handful have survived as cities to this day. Cusco in southeastern Peru was a city of great importance long before the European arrival to the continent. The Inca Empire flourished in ancient Peru between the 13th century and the Spanish conquest in the 16th century and Cusco was the Empire's capital. Particularly notable is the colonial architecture in Cusco as many buildings used the city's Inca constructions as a base (pictured).

In the city, Inca sites stand shoulder to shoulder with colonial mansions and Catholic churches, but it's impossible to talk about Cusco and not mention Machu Picchu, another Inca citadel, located just 50 miles (80km) from Cusco. Founded in the 15th century as a royal estate for Inca rulers outside Cusco, Machu Picchu was abandoned during the Spanish conquest and due to its remote and mountainous location wasn't rediscovered until 1911. Take a look at other world's amazing lost cities recently rediscovered.

One of Japan's most historic and oldest cities, Kyoto is the former ancient capital of the country. A city of ornate temples, sacred shrines, well-preserved historic neighbourhoods and classical gardens, it's home to some of the country's best-preserved historic landmarks. Though the centre is fairly modern, the city’s historic districts are as beguiling and beautiful as ever, especially Arashiyama, home to bamboo groves and pagodas, and Gion and Pontocho, known for the geisha culture and many traditional tea houses.

About 20% of Japan's National Treasures can be found in Kyoto. Among them are 11th-century Byodo-in Temple, the 1,300-year-old shrine Fushimi Inari Taisha and the golden Kinkakuji Temple, also known as the Golden Pavilion. The site was originally a villa belonging to a powerful Japanese statesman. In 1397, it was purchased by a shogun (Japanese military dictator) and transformed into the complex we see today. The present pavilion structure dates from 1955, when it was rebuilt following an arson. Here are 40 unmissable things to see in Japan.

As the capital of the Roman Empire, Rome is a treasure trove of ancient riches. One of its most recognisable landmarks is the mighty Colosseum (pictured). The amazingly well-preserved amphitheatre was built in the 1st century to host games, gladiator tournaments and public spectacles, however, it's the Palatine Hill that's one of the city's most ancient and important. It's supposedly where Romulus and Remus, legendary founders of Rome, were raised by the she-wolf and it also has some of the city’s most important archaeological ruins including villas and palaces, where many emperors and wealthy Romans resided. 

Right next to the Colosseum lies the remains of the Roman Forum (pictured), centre of ancient Rome’s public and political life. The vast and atmospheric complex contains temples (including the Temple of Saturn and the Temple of Vesta), squares and numerous arches (including the grand Arch of Septimius Severus, dedicated to the emperor’s victories against the Parthian Empire in ancient Iran in the 2nd century AD). Now discover little-known incredible Roman ruins around the world.

Any exploration of Greece’s astounding history has to start in Athens – the cradle of modern democracy. The Greek capital was also the birthplace of theatre and is still home to the remains of some of the earliest theatres. The Herodion Theatre was constructed by Greek nobleman Herodes Atticus on the slopes of the Acropolis in AD 161. But the Theatre of Dionysus (pictured) is even more ancient – in fact, it’s the world's first theatre.

Nothing screams Athens like the Acropolis, the rocky hill that's loomed over the city since the 5th century BC, home to some of antique period's greatest buildings, including the iconic Parthenon. The Doric temple was one of the first monuments built here when it was constructed between 447 and 438 BC. It was dedicated to Athena Parthenos, the patron of the city. Today, the sculptures of the Acropolis are housed in the gleaming, state-of-the-art Acropolis Museum, to protect and preserve them. Read 22 new secrets of the world's ancient wonders.