The Southern California Counties Building was located on the north side El Prado, adjacent to the Panama-California Exposition's Plaza de Balboa. The building was designed in an eclectic Spanish-Colonial style, featuring a large central structure with flanking tile-roofed wings, which extended south and enclosed an arcaded patio, paved with rough Mission-tile. The patio was entered on its south side through a heavily ornamented portal, which formed the building's main entrance. The north wall of the patio featured a two-storied arcade, similar to one found within the patio of the Convento de San Agustin, located in Queretaro, Mexico. The upper portion of the arcade was enclosed with large arched windows, surrounded by Spanish Baroque ornamentation and topped with a heavy cornice. Located at the north angles of the patio were two Spanish Baroque towers, each featuring semi-circular balconies, decorative finials, and blue, black, and yellow tiled domes. On the north side of the building was a smaller tile-paved patio, located within a tile-roofed wing, overlooking a large formal garden with hedge-framed planter beds, filled with numerous varieties of flowers. At the building's west side, facing Calle Cristobal, a grand staircase led to an imposing Baroque-style entrance, with an ornamented balcony situated above. The spacious structure housed exhibits from the seven counties of Southern California, in addition to a large lecture hall, and several reception and meeting rooms.