A Definitive Ranking of the Top 10 Sights in the World

Church, mosque, and museum in one, Aya Sofya is a structure unlike any other on the planet — defying easy categorization just as it defied the rules of architecture when it was built almost 1,500 years ago. The man behind it all was Byzantine Emperor Justinian I: he demanded a cathedral to eclipse the wonders of Byzantium's sister city, Rome, and moreover, one that would mimic the majesty of the heavens on earth. He got his wish, and Aya Sofya still dominates the skyline in modern-day Istanbul.

The countdown doesn’t stop there — check out the top 11 to 20 in our ultimate travel list for more unmissable sights and perhaps a few surprises. View the complete list of the 500 best sights on the planet in our new title Ultimate Travel, which is available now in Lonely Planet's shop and where books are sold.

Originally published as "Ultimate Travel List: Lonely Planet's Top 10 Sights in the World" © 2015 Lonely Planet. All rights reserved.