Karakorum

"At Sarai in the land of Tartary,

There dwelt a king who warred on Muscovy,

Whereby there died full many a doughty man.

This noble king was known as Cambuskan."

Chaucer

Although originally built by Ghengis Khan as a command post for his invasion into China, it was his son and successor, Ogodei, that rebuilt and re-established Karakorum in emminence on the Silk Road. Under his rule, the city became a major center of trade and politics.
When Kubilai Khan moved the capital to Dadu (China) in 1260, Karakorum fell into decline and was eventually invaded by Chinese and destroyed, though it was never completely abandoned.

What withstood the winds of time and warfare was incorporated into the construction of the Erdene Zuu monastery. The monastery was founded in 1586 following the adoption of Buddhism as the official state religion. Through the ages it has suffered but the majority of the damage, from which it has not recovered, occurred during the state religious purges of the 1930's. It is now a museum and houses religious artifacts that survived or were hidden during the turmoil of the communist era.
All that remains of the monastery are a handful of buildings and the vast stone wall, topped by 108 stupas.

This is what most people come to see when they visit Hahorin, not the inside of a hospital.