Lower, and in 1897 the practice moved to the Osborn Building on Prospect Avenue, downtown Cleveland. A four-story outpatient building was constructed, and Cleveland Clinic was dedicated at a private ceremony on February 26, 1921. It opened its doors two days later to the public and registered 42 patients. By April 1921, it had 60 employees, including 14 physicians and four nurses. In 1922 the founders purchased four private homes nearby for hospitalization, radiation treatment, and administration. A fifth house was acquired as a residence for patients with diabetes receiving insulin treatments. To meet rising patient volume, a 184-bed hospital was built in 1924, located at East 90th Street and Carnegie Avenue. A power plant, laundry, and ice plant were also built. A research laboratory was constructed in 1928. Cleveland Clinic fire On May 15, 1929, nitrocellulose x-ray films stored in the basement of the outpatient building ignited. An explosion sent a cloud of toxic oxides of nitrogen and carbon though the building. One hundred and twenty-three people, including John Phillips, one of the founders, lost their lives. A dozen investigating agencies were not able to determine what had caused the fire. Cleveland Clinic's own inquiry narrowed the possible causes down to spontaneous combustion caused by heat; a discarded cigarette or match; and contact with an extension cord light hung over a stack of films. Philanthropist Samuel Mather formed a committee of 36 community leaders to help Cleveland Clinic reestablish itself in temporary quarters across the street. Patient care services resumed five days later. The 1921 building was completely renovated, and a new three-story clinic building, with a new main entrance, was added in 1931. All debts were repaid by 1941. Growth of specialization Cleveland Clinic built new operating rooms in the early 1970s to accommodate the growth of cardiac surgery. The Martha Holden Jennings Education Building opened in 1964, with an auditorium named for Dr. Bunts. A new hospital building (currently home to Cleveland Clinic Children's Hospital) opened in 1966, and a research building opened in 1974 (demolished in 2007). A pathology and laboratory medicine building was constructed on Carnegie Avenue in 1980. Willian S. Kiser, chairman of the board 1977–1989, led the development of a strategic plan to accommodate growing patient volumes in the late 1970s. This resulted in a group of buildings known as the Century Project. Completed in 1985, the Century Project includes a 14-story outpatient