The Cathedral Square is located in front of the Cathedral of Barcelona, in the district of Ciutat Vella, in the heart of the historic centre of Barcelona.
In this square we can still see a section of the Roman wall of Barcelona. This wall was built during the fourth century AD, and replaced the wall that had been built in the founding of the colony of Barcino, during the first century BC. Along the Cathedral Square, we can see several quadrangular towers that were part of the Roman wall.
We can also see the Decuman Gate, which is located in the Cathedral Square with the Bisbe Street. This gate was the northwest entrance to the Roman city of Barcino, and is flanked by two circular towers. In archaeological interventions at this point, has been found the remains of three side doors, two for pedestrians, and the centre door for cars. If we look closely, to the right of the current ramp, we can see, behind a fence, the remains of one of these doors.
In the left tower, you can see the last arcade of the Roman aqueduct. It should be said, therefore, that this arcade is not original, but was a reconstruction made in 1958. The original entrance to the Roman aqueduct would be where the chapel of Sant Roc is located.