In 1941, workers digging a wartime bunker in Cologne broke through the floor and found a Roman dining room, perfectly intact beneath the city. On its floor lay a mosaic of over 1.5 million tiny stones, laid there 1,800 years earlier. Dionysus, the god of wine, sits at its centre, surrounded by seasons, birds and fruit. The mosaic was never moved. The museum was built around it.

Also inside stands the tomb of Lucius Poblicius, a Roman soldier from southern Italy who died around 40 AD. Nearly fifteen metres tall, it was unearthed in the 1960s by amateur archaeologists during a construction project, who then sold it to the city.

VoiceMap's self-guided audio tours use the museum to trace Cologne's Roman origins, revealing how a frontier city founded in 19 BC became one of the empire's most prosperous outposts.