Barcelona Cathedral was started in 1298 on the site of a former Romanesque cathedral, which was supposedly built on the site of a Paleo-Christian chapel dating to the 4th century. The Gothic building was completed in 1459 and the dome and front facade were completed in the late 1800s. Inside the church is the tomb of Saint Eulalia, as well as many fine paintings and precious metalwork. The main altar is wooden and dates back to the 15th century. The Cathedral is the most prominent building in an area called the Gothic Quarter an important historic center for Barcelona. If you like detail, scrollwork, and lattice work, you will like this area. Gothic structures are defined as least in part by "frilly" wood and stone work.
Other buildings in the area include the Casa de la Pia Almoina built in the 15th century. Next to the Cathedral on one side is the Frederic Mares Museum and a little further on is the Clariana Padellas house with contains the City History Museum. This museum has Roman, Visigoth and Moorish remains in it. Also in this immediate area is the Placa del Rei, which is a medieval site and also contains the archives of the crown of Aragon. The Chapel of Santa Agueda, which is also a 14th-century Gothic church, is also here. On the other side of the Cathedral is the Casa de l’Ardiaca and a unique historic site called the Deacon’s house, which was built in the 12th century over one section of the old Roman walls.
All in all, many buildings, many old buildings and many famous parts of old buildings. I could not keep it all straight in my head till I saw a map of the places we were visiting. So, I took a picture of that map and included it here. In short, the Gothic Quarter and the Barcelona Cathedral specifically represent the medieval to renaissance sections of the historic district of Barcelona. There is also a fragment of a Roman temple to Apollo in the courtyard area in front of the main facade of the Cathedral. Four columns are all that’s left but it’s interesting that these are even here with all the Christian church building that went on in the area. Also, on the backside of the Cathedral is the remains of the old Roman wall of the old city. In the picture below, it is the lowest strata of rock and frankly looks old!
One last thing . . . I’m going to try and tell you WHERE the Gothic quarter is! Most maps will have the Plaza de Catalunya clearly marked. (It is at one end of the Ramblas) There is a street named Ave. Portal de l’Angel. Head towards the ocean or east on that and it will dead end into the Cathedral and the Gothic Quarter.