Roman Theatre of Lisbon
Near the Castle is the Roman Theatre and you find it almost by accident. In this case the 1755 earthquake played a positive role as the ruins of the theater were discovered after the earthquake (they had been buried since it was abandoned in the fourth century AD). But during the reconstruction of the city, although difficult to understand, buildings were erected on these Romans remains, so it wasn't until 1964, when several buildings were demolished that excavations began.