Witness Albert Einstein and Robert Millikan at the opening ceremony of the Mount Palomar Observatory 1948

This 1948 video shows the opening of the Mount Palomar Observatory, near San Diego. For decades the observatory's 200-inch reflector was the world's largest telescope. Its primary mirror weighed 14 tons and took 13 years to make, and, as the video shows, assembling the telescope was a massive engineering undertaking. The opening ceremonies were attended by many prominent scientists, including physicist Albert Einstein, shown here talking with fellow Nobel laureate Robert Millikan.