http://en.wikipedia.org/wiki/Skara_Brae
Skara Brae had been abandoned for 1200 years when Troy fell!
For a building that can actually be used, how about this: http://en.wikipedia.org/wiki/Tower_of_Hercules (1900 years old) or the Pantheon http://en.wikipedia.org/wiki/Pantheon,_Rome (~1900 years).
Although my favourite is Hagia Sophia: http://en.wikipedia.org/wiki/Hagia_Sophia - a youngster at almost 1500 years old.
The other buildings are in daily use though, which is why I used them instead of old Roman buildings and such.
http://en.wikipedia.org/wiki/Skara_Brae
Skara Brae had been abandoned for 1200 years when Troy fell!
For a building that can actually be used, how about this: http://en.wikipedia.org/wiki/Tower_of_Hercules (1900 years old) or the Pantheon http://en.wikipedia.org/wiki/Pantheon,_Rome (~1900 years).
Although my favourite is Hagia Sophia: http://en.wikipedia.org/wiki/Hagia_Sophia - a youngster at almost 1500 years old.