We enjoyed the drive up the mountain and take part in a private, docent-led tour of Mount Wilson Observatory, high above Pasadena. The Observatory contains two historically important telescopes: the 100-inch (2.5 m) Hooker Telescope, with was the largest aperture telescope in the world from its completion in 1917 to 1949, and the 60-inch telescope which was the largest operational telescope in the world wen it was completed in 1908.