Sri Lanka’s ancient capital, this UNESCO site dates back to the 4th century BC. It’s crammed full of monasteries, palaces and statues of Buddhas. And it’s no small scale operation. In fact, it covers an area of over 16 square miles – that’s about the size of central London. Don’t miss the legendary Bo tree near here, which has been guarded 24/7 for the last 2,000 years.