Ubii Monument

This guide to the Ubii Monument in Cologne opens in 1965, when construction workers fifteen meters under modern Cologne struck stone from a Roman fort no record had ever described. It follows the corner tower of the Oppidum Ubiorum, raised around four or five AD on oak piles driven into the Rhine's wet ground, and asks why later generations named it for a Germanic tribe that arrived here before the tower existed. You'll hear about Marcus Agrippa ferrying that tribe, the Ubii, across the Rhine decades earlier, and how Roman masons locked the stone without mortar. Look at the surviving stretch of the corner you're standing beside.