Braga stands on the ruins of Bracara Augusta, founded by the Romans around 16 BC and eventually one of the four capitals of Roman Hispania. This museum, housed in a purpose-built modern building, holds the best surviving collection from those excavations: altars, inscriptions, mosaic fragments, coins, and sculpture pulled from the ground beneath the city.
The displays are well-organised and the labelling is in Portuguese and English. Particularly striking are the carved stone altars with Latin dedications to local deities, and the scale model of Bracara Augusta at its Roman peak, which helps you picture the grid of streets now buried beneath the medieval city. Plan an hour here before exploring the centre — you'll see the old town differently afterwards.