St. Gereon

This guide to St. Gereon in Cologne moves between two brushes with collapse eight centuries apart, starting from a Roman burial ground that became, sometime between 350 and 365, an oval hall ringed with niches said to honor martyred soldiers of the Theban Legion. You'll hear how a medieval legend gave that story its name and its saint, and how builders working between 1219 and 1227 chose to wrap the fragile Roman oval in new stone rather than tear it down. The guide also follows the 1944 bombing raids that cracked the dome above it and the decades-long repair that came after. Look for the exposed strip of Roman foundation on the north side, still visible beneath the later stone.