The most striking building in the Plazuela de San Marcelo is the Casa de Botines on the north side of the square, a Neo-Gothic building by the Catalan architect Antoni Gaudí (1894). It is now occupied by a bank.
On the northeast side of the Plazuela de San Marcelo stands the Palacio de los Guzmanes (1560), a building in the style of an Italian palazzo which is now occupied by the Diputación Provincial. It has an imposing facade, with round-headed arches, large corner towers and wrought-iron balconies.