Please answer the following question: Question: "When were the buildings ready but not used?"  Context: "In 1899, the university opened a national design contest for the new campus. The renowned Philadelphia firm Cope & Stewardson won unanimously with its plan for a row of Collegiate Gothic quadrangles inspired by Oxford and Cambridge Universities. The cornerstone of the first building, Busch Hall, was laid on October 20, 1900. The construction of Brookings Hall, Ridgley, and Cupples began shortly thereafter. The school delayed occupying these buildings until 1905 to accommodate the 1904 World's Fair and Olympics. The delay allowed the university to construct ten buildings instead of the seven originally planned. This original cluster of buildings set a precedent for the development of the Danforth Campus; Cope & Stewardson’s original plan and its choice of building materials have, with few exceptions, guided the construction and expansion of the Danforth Campus to the present day."  Answer:
A:
1904