Let me introduce you to Tartaria.

The globalized version of the conspiracy theory is based on an alternative view of architectural history. Adherents propose that demolished buildings such as the Singer Building, the original New York Penn Station, and the temporary grounds of the 1915 World's Fair in San Francisco were actually the buildings of a vast empire based in Tartary that has been suppressed from history. Sumptuously styled Gilded Age buildings are often held out as really having been built by the supposed Tartaria. Other buildings, such as the Great Pyramids and the White House, are further held out as Tartarian constructions. The conspiracy theory only vaguely describes how such a supposedly advanced civilization, which had reputedly achieved world peace, could have fallen and been hidden.[5][6] Proponents of the theory also frequently claim that Tartarians have developed unlimited wireless energy.