Plaça del Rei

In front of you is the courtyard of the Palau Reial Major, home of the counts of Barcelona, who from 1137 were also kings of Aragon. From these walls they ruled a crown that came to stretch across Majorca, Valencia, Sicily, Sardinia and Naples.

1The hall of great arches

The steps at the far end lead up to the Saló del Tinell, built in the mid-14th century on the orders of Peter the Ceremonious. Its architect, Guillem Carbonell, roofed the hall with six huge diaphragm arches, a solution that spanned a great width without any columns. This was the court's hall for receptions and banquets.

To the right stands the palace chapel of Santa Àgata, from the early 14th century, with its octagonal bell tower. Above it all rises the gallery tower known as King Martin's Watchtower; despite the name, it was built in the 16th century, long after the death of Martin the Humane.

2A buried city

In 1931 the Casa Padellàs, a Gothic mansion from Carrer Mercaders, was moved here stone by stone. When its foundations were dug, a whole Roman town turned up beneath the square. That is why, since 1943, the building has housed the Barcelona City History Museum, and why, under your feet, you can walk along the streets, workshops and wine cellars of Barcino.

Much of the medieval history of the Crown of Aragon was written here, and the Roman town sleeps beneath the square.

3What to look for

• The fan-shaped staircase leading up to the Saló del Tinell.
• King Martin's Watchtower, with its five storeys of galleries.
• The octagonal bell tower of the chapel of Santa Àgata.