It's altitude is about 11,000 feet! We took some altitude medication and it probably helped. But getting there by plane (the only realistic way) is an abrupt transition since the Lima airport is at sea level. The last time we went there we arrived early in the morning and went touring about all day and we were exhausted. That night I could hear and feel my heart beating all night. This time we took it easy on the day of arrival and that was a help.
The rainbow flag seen all over is the official flag of Cusco - or Cuzco as it is sometimes spelled. It represents Inca territory and likely has long-ago historical significance. There is some evidence form the Spanish invasion in 1534 that such a flag or something similar was present. The Incas had no writing so it is quite difficult to determine accuracy of historical information - leading to much controversy - particularly about Machu Picchu.
The main square is called Plaza de Armas as it is in many other hispanic countries. Our hotel was a couple of blocks away. (It was slightly uphill to the square which made coming back easier). There is lots to see including convents, museums, just walking around in this busy city - and some excellent restaurants as well. And there are side trips to nearby Inca structures and other things.
Click here for some pictures