The mineral springs that gave Sulphur, Oklahoma its name once attracted thousands of visitors a year as a health spa. The Bromide Pavilion at the southern edge of the Platt District is the surviving centrepiece — a small stone-and-timber structure built in 1936 by the Civilian Conservation Corps, with two spouts that originally dispensed bromide and sulphur water.
The springs themselves are no longer flowing reliably, but the pavilion and the well-shaded surrounding grounds make a good stop on a walking tour of the eastern district. Several smaller CCC-era structures — Pavilion Springs, Hillside Spring, Black Sulphur Spring — sit nearby. Together they form one of the largest collections of CCC architecture in any US national park unit, and the Platt Historic District was added to the National Register of Historic Places in 2011.