The ruins of an ancient Roman theatre built into one of the slopes of São Jorge Castle enable us to see the marks of history on the city, transporting us back to Olisipo at the beginning of the 1st century AD. Abandoned a few centuries later and rediscovered thanks to reconstruction efforts after the 1755 earthquake, it was transformed into a museum, inaugurated in 2001 as the Roman Theatre Museum, and became part of the Museum of Lisbon in 2015. Comprised of two buildings, this “on-site museum” includes an area for long duration exhibitions and an archaeological site.