|Lowell Observatory is an astronomical observatory near Flagstaff, Arizona. It was founded in 1894 by astronomer Percival Lowell.|
The observatory operates several telescopes at two locations in Flagstaff. The main facility, located on Mars Hill just west of downtown Flagstaff, houses the original 24-inch (.61-metre) Clark Refracting Telescope.
The telescope is listed as a US national historic landmark. Also located on the Mars Hill campus is the 0.33-metre Pluto Discovery Telescope, used by Clyde Tombaugh in 1930 to discover the planet Pluto.
The second observation site, atop Anderson Mesa, houses four telescopes, including a 1.8-metre Perkins telescope that it shares with Boston University, the 1.1-metre Hall Telescope and the Navy Prototype Optical Interferometer (NPOI).
The still to be built Discovery Channel Telescope will be located at a site known as Happy Jack.