- ;Built in Salt Lake City, Utah 1869
- ;Replicated in 2001
On Sept 30, 1869, George W. Dean of the U.S. Coast and Geodetic Survey established this building as an observatory for Meridian Line Placement. Originally located on the southeast corner of Temple Square, this building also contained astronomical equipment and was used to tell time until 1897. This replica is named for pioneer scientist Orson Pratt, who created the street grid of Salt Lake City in 1847.