Lowell Observatory - Flagstaff, Arizona

The Lowell Observatory is fantastic to visit, with many interesting artifacts and instruments. Percival Lowell was a fascinating 'renaissance man' who built the telescope (below), using the world's best lens-makers (at the time) and the local town's finest metalworkers.

Lowell had done a lot of the groundwork in locating/discovering Pluto, but it was Clyde Tombaugh who did the discovering on the astrograph (below).

After knocking himself out one night, Tombaugh added some padding onto the astrograph (below)