The Sobrellano Palace was built between 1881 and 1890 for the first Marquis of Comillas, Antonio López y López, one of the wealthiest men in 19th-century Spain — a fortune built largely on transatlantic trade and shipping, including, before abolition, the slave trade. The building was designed by Joan Martorell, the same architect responsible for the Pontifical University on the hill above, in a severe neo-Gothic style with pointed arches and stone towers that give it the look of a medieval castle.
The interior is remarkable for its furniture: Gaudí designed pieces specifically for the palace that remain in place today, including carved chairs and a cabinet that show his early decorative sensibility. The adjacent Chapel-Pantheon, also by Martorell, was built as the family mausoleum and contains sculpture by the Catalan artist Josep Llimona. Both the palace and chapel are managed by the Cantabrian government and can be visited by guided tour; check locally for schedules as they are limited.