Palomar Observatory
Home to the historic 200-inch Hale Telescope, for decades the largest in the world, set atop forested Palomar Mountain. Daytime visitors can view the great dome, browse exhibits, and take guided tours. The drive up is winding and scenic; check road and weather conditions in winter.
35899 Canfield Rd, Palomar Mountain, CA 92060 (CA, San Diego)

