Located in the centre of the Gothic Quarter, the Palacio Real Mayor de Barcelona was a former royal residence in Spain that stood in the Plaça del Rei. It was the residence of the counts of Barcelona and later of the kings of the Crown of Aragon.

The name Palau Major is first documented in 1116, and was so named to distinguish it from the Palau Reial Menor, which was built in Plaça de Sant Miquel, behind the Casa de la Ciutat, and which was demolished in 1847.

Of the old complex, only a few isolated and much transformed buildings remain, which are open to the public as part of the Museum of the History of Barcelona and the Frederic Marès Museum.

The palace dates back to the Visigothic period, the remains of which can be found under the Salón del Tinell. In 985, this first palace, along with the rest of the city, was sacked by Almanzor, a soldier of the Caliphate of Córdoba.

During the second half of the 11th century, the building was demolished to build a new one. The Romanesque building was rectangular and perpendicular to the wall to which it was attached. The palace stretched from the Romanesque cathedral to what is now St. Ivo's Square. The external staircase, which still exists today, dates from this period, where the meetings of the Council of One Hundred were held when they did not yet have their own building.

This Romanesque palace remained unchanged for nearly two centuries without undergoing any major alterations.

The layout of the palace is based on three buildings: the Saló del Tinell, the Palatine Chapel of Santa Agata and the Lloctinent Palace.

The Salón del Tinell was ordered to be built by King Peter the Ceremonious between 1359 and 1362 by master builder Guillem Carbonell. It has a rectangular floor plan measuring 34 metres long by 17 metres wide and 12 metres high, covered with a flat roof with wooden beams resting on six semicircular stone arches with moulded profiles on attached columns with capitals and with a span of more than 16 metres between them.

The palatine chapel of Santa Agata, dating from 1302, the work of King James II of Aragon and his wife Blanca of Naples. Inside is the altarpiece of Constable Pedro de Portugal by the painter Jaime Huguet.

The Lloctinent Palace, built in 1549 and commissioned by King Charles I to Antoni Carbonell, was the headquarters of the General Archive of the Crown of Aragon from 1836 to 1994.