The Chapel of Santa Agata is a beautiful 14th century church, composed of a single Gothic aisle with main arches supporting a polychrome wood coffered ceiling. The high altar contains a masterpiece of Catalan art by Jaume Huguet (1464) featuring themes from the Adoration of the Magi and the Crucifixion, known as the Constable Retablo. At the end, under a large arch, is the semicircular stairway leading to the Royal Palace. The former sacristy has a large iron mechanical clock dating from the year 1576. The old windows in the choir and gallery show the various coats-of-arms of the counts of Barcelona.