All four classical elements combined to shape architect Hawkins\Brown’s new swimming pool for the City of London Freemen’s School, set in the grounds of a former country estate in Ashtead, a leafy suburb. The dark, low-slung building is partly embedded in the earth of its sloping site, minimizing its outward impact, but from the water swimmers enjoy the airiness of a light-filled enclosure whose pale wood portal frames arch overhead like the ribs of a gothic vault. And it was the fourth element—fire—that initiated the project, after the school’s previous pool building burned down in early 2014.