i saw this on PBS and fornd it amazing!
Chaco Canyon and related buildings might be the oldest in the US, AD 900 and 1150
"Some believe that a mysterious stone tower in Newport, RI, is the oldest building in America, built by the Vikings around AD 1050. Most academics think that it was built by a Colonial farmer, or by refugees of a Chinese treasure ship, but since no records exist, how do they know? "