The earliest known structure built by human-like creatures is a circle of stone blocks that was found in Africa. This “structure” may have been erected as long ago as 1,750,000 B.C.
The earliest known buildings, a series of huts containing fireplaces, were recently discovered in France. However, all that remains of these buildings are their outlines on the ground. That’s not surprising, as they may have been constructed as early as 120,000 B.C.
In the 1980s, some of the oldest buildings still standing were unearthed on the island of Malta in the Mediterranean. They are temples made of limestone slabs, and were probably built before 3000 B.C.
As for remains, there’s part of a tower in the city of Jericho, in Israel, that dates back to around 5000 B.C.
The oldest buildings recently discovered are in Eridu (Tell Abu Shahrain) and Ur, ancient cities in modern Iraq, there are still building that have been excavated that date back to as early as 5000 B.C., or ~7000 YBP.
In Ur there are still buildings as old as 4000 B.C. Complete tombs and temples at Hierakonpolis date back as old as 3600 B.C.