The intersection of the cardo and decumanus, the main streets of the Roman city of Barcino, was the site of the forum and the Temple of Augustus, whose four columns are still visible on Mont Tàber. This area is now known as Plaça Sant Jaume, named after the church of the same name that was built there in medieval times. The city council of Barcelona used to meet on the porch of the church until they purchased nearby homes to serve as their headquarters.
In the past, the square was a small angular space, as the rest of the area was occupied by the church, its cemetery, and the houses of the Magistracy and the General Court of the Veguer. However, the demolition of the church in 1823 allowed for the square to be expanded to its current size. At different points in history, Plaça Sant Jaume has been referred to as "Constitution Square," a name that was displayed on a plaque on the City Hall's façade until its removal in 2013.