Artist Oskar Hansen works on Monument Plaza at Hoover Dam, which he created for the 1935 dedication. The plaza floor is a giant star map, indication the positions of key stars at the moment of the dedication (left images). The layout is festooned with astronomical details, including a depiction of the Pleiades star cluster and its brightest star, Alcyone, shown at the time of the dedication (top left) and in more modern times (right). (U.S. Bureau of Reclamation (3); Jeremy Faludi/Wikipedia (right))