Built by the Dutch East India Company between 1666 and 1698, the Castle of Good Hope is South Africa's oldest existing colonial building. Following extensive restoration work in the 1980s, the bastion fort in Cape Town was returned to how it would have looked when it was first constructed. You'll be hard pressed to find a better-preserved piece of 17th-century architecture anywhere in the world. That view of Table Mountain in the background isn't bad either.

Now discover the secrets of the world's most beautiful mountains

Stunning castles you've never heard of