Opposite the southeast end of La Catedral, narrow Carrer del Paradis leads towards Plaça de Sant Jaume. Inside No 10, an intriguing building with Gothic and baroque touches, are four columns and the architrave of Barcelona’s main Roman temple, dedicated to Caesar Augustus and built to worship his imperial highness in the 1st century AD.

You are now standing on the highest point of Roman Barcino, Mont Tàber (a grand total of 16.9m – unlikely to induce altitude sickness). You may well find the door open outside the listed hours.