By World War I, attendance in the school was rapidly increasing. An annex was added on 26th Street to alleviate overcrowding in the Howard Street building, but it was insufficient. Therefore, during the 1920s, alumni began campaigning to provide a proper building for the school, and in 1926, ground was broken for a massive Collegiate Gothic stone castle with a 38-acre (153,781 m2) campus, on a hill in the newly annexed northeastern suburbs at 33rd Street and The Alameda. The four-level "Castle on the Hill", which was surmounted by a 150 ft (46 m) tower and designed by architects Buckler and Fenhagen, cost almost $3,000,000 and accommodated 2,500 students. The "castle" featured arched windows and cornices, cloisters, gargoyles, stained glass, mahogany paneling, plaster arches, chandeliers and terra cotta tiles and terrazzo floors with two courtyards and plans for additional wings and buildings.