Mount Wilson (California) a new Mt. Wilson Hotel. In 1908 a 60-inch (1524 mm) telescope was completed at the summit, and in 1910 the Solar Tower was erected. In 1913 the hotel burned down and was replaced by a second hotel that lasted until its demolition in 1966. The Toll Road opened to automobiles in 1912 and lasted until 1936. In 1917, the 100-inch Hooker Telescope was completed and saw first light and would be the world's largest telescope until the opening of the 200-inch Hale Telescope at Palomar Observatory in 1948. In 1919, American astronomer Edwin Hubble arrived at Mt. Wilson and,
Telescope coated glass mirrors in 1857, and aluminized mirrors in 1932. The maximum physical size limit for refracting telescopes is about 1 meter (40 inches), dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors. The largest reflecting telescopes currently have objectives larger than 10 m (33 feet), and work is underway on several 30-40m designs. The 20th century also saw the development of telescopes that worked in a wide range of wavelengths from [[radio telescope|radio]] to [[gamma-ray telescope|gamma-rays]]. The first purpose built radio telescope went into operation in 1937.