Construction began on Old Main in 1894, and it was dedicated in February 1898. The building was originally all classrooms on the second and third floor, with an auditorium (the Assembly Hall) on the upper floor and a library on the lower level. In 1911,
Theodore Roosevelt came to Arizona for the dedication of the
Roosevelt Dam, and spoke on the steps of Old Main. In his speech, he envisioned the opportunities the dam and the resulting irrigation for farming would create for Arizona and opined that some day perhaps as many as 100,000 people might live in the valley. The dam made possible the
Salt River Project and eventually led to the evolution of the
Salt River Valley as a major metropolitan area. For decades, Old Main was the largest building in the
Salt River Valley. Its significance to the development of both Tempe and the university was great. After Old Main was built, alumni went to the legislature to ask that the admission standards be raised, in order to bring the stature of the institution up to the stature of the building. The designation of Old Main as a historic place with its listing on the National Register of Historic Places in 1985 – the year of ASU's centennial – provoked interest in restoring and renovation the building. Efforts began in 1990, and by 1996 it had become an important part of the university’s $400 million "Campaign for Leadership". Thanks to a $5.7 million campaign led by the ASU Alumni Association, the building was refurbished to the period in which it was constructed. ==Architecture==