The Museum of the History of Barcelona has several sites around town, this being the central one. Here you can get a fascinating look at ancient Roman times through a tour of underground walkways over the excavations of Barcino, the city founded in the 1st century B.C. (the Moors leveled it in the A.D. 8th c.). It’s set in part of the 11th-century Palau Reial Major, palace of the kings of Aragón and Catalunya (also in this palace complex: the Museu Frederic Marès). Although they are partially visible from Plaça del Rei, the last remaining Roman walls and defensive towers of Barcino—a section from the A.D. 4th-century second enclosure—are easier to make out from the museum’s other side, on Plaça Ramon Berenguer on Via Laietana. Embedded within the wall are the royal chapel of Santa Ágata and a 14th-century segment of the Palau Reial.