The world's most-visited ancient ruins

Pyramids of Giza, Egypt
As one of the original Seven Wonders of the World and certainly the symbol of Egypt, the Pyramids have been venerated for 4,500 years. But how the ancient Egyptians built them is unknown, which adds to their intriguing appeal. The three major tombs for pharaohs that rest at this Unesco World Heritage Site are now surrounded on three sides by the pressures of Cairo, a city teeming with nearly 11 million people. Annual visitors: four million (Richard I'Anson/LPI)

Terracotta Army, Xi'an, China
Discovered in 1974, these 700 life-size terracotta generals, infantrymen, archers and chariot drivers are each unique, with distinct facial features, hairstyles and clothing. The clay statues were arranged in rows in covered pits as part of a necropolis for Emperor Qin Shi Huang. More are believed to still be buried, but work on removing and restoring the soldiers has been halted until a way can to found to keep their bright paint from fading in the air. Annual visitors: 3.6 to 4.5 million (Dean Waites)

Roman Forum, Rome
The social centre of Rome for 1,200 years beginning in the 5th Century BC, this 700-yard-long piazza has been both a marketplace and a government centre. The ruins of sacred temples' columns and friezes (whether dedicated to Saturn, the god of agriculture, or to the emperors Vespasian and Titus) hint at the Forum's level of grandeur two millennia ago. Annual visitors: 5.1 million (Sathaporn Srichuwong)

Colosseum, Rome
When completed in 80 AD, the arena held 50,000 spectators who watched mythical dramas, re-enactments of land and sea battles, executions, fights-to-the-death and the ghastly slaughter of wild animals. The underground pits where gladiators awaited their fates were opened to visitors in 2010, along with the 110ft-high upper ring of seats, which offer panoramic views of the Eternal City. Annual visitors: 6.9 million (Alexander Borais)

Great Wall, Badaling, China
With a name so simple, yet so powerful, the Great Wall stretches for 5,500 miles across China. Its most beautiful section is also easily accessible — within 70 miles of Beijing. While much of what is visible today was built during the Ming Dynasty (1368 to 1644), construction began on various sections as far back as 770 BC. Annual visitors: 9 to 10 million (Rad Danesh)