The 63rd Street Bathing Pavilion is a long, rectangular building – 460 feet in length and 145 feet in width – with roofs covered by contemporary green tiles, replicating the building's original roofing. The four corners of the building terminate in square pavilions topped by pyramidal roofs with wide overhangs very similar to the building's higher central towers. The building is symmetrical composed, with a central two-story mass flanked by two enclosed courtyards. Enclosed by high walls, the courtyards originally were the changing locations and shower accommodations for bathers, one for men, the other for women, with lockers and dressing rooms that could serve 2,044 women and 3,903 men. The walls of the building are constructed entirely of poured aggregate porous concrete, giving the structure a feeling of great permanence and strength. The building material – a form of an exposed aggregate reinforced concrete which had become known as"popcorn concrete" or 'marblecrete" – was an inexpensive material from which buildings could be constructed rapidly, and was used widely by the South Park Commission. The central block of the building consists of a two-story loggia with an open arched second story bracketed by twin towers. Covered by a gable roof supported by an impressive open metal truss, the loggia is detailed by classical
pilasters on its park and beach elevations, is topped by a classical
balustrade on its park elevation, and has classically inspired brackets on the building's beach elevation. Detailed by Tuscan columns, the towers are covered by pyramid-shaped roofs with very wide eaves supported by wooden brackets suggestive of the Prairie style. Similar but slightly smaller towers flank the building's entrance on the park side. Today, the two courtyard spaces are open, the south courtyard landscaped by turf, the north by a water fountain. The beachside wall of the courtyards still includes its original ironwork railings and serves its original purpose, offering a long promenade overlooking
Lake Michigan. ==Historical context==