Several prehistoric settlements and remains of a Roman road station have been discovered in Welschdörfli, the old town district south of the Plessur. You can visit the excavations and discoveries on the Ackermann grounds on Seilerbahnweg.
The protective structures covering the archaeological sites from the Roman era were built in 1986 according to designs by local architect Peter Zumthor. They do not only protect the finds, they are also a museum and architectural masterpiece. The weighty building with its delicate rilled outer surface is reminiscent of the original Roman edifices.
You can get the key to the protective structures from the Chur Tourism information centre at the station for a fee of CHF 3.00 and a deposit of CHF 50.00. Chur Tourism also offers interesting tours of the excavations.