Watercolor, date unknown (via UNC)
1836 map by Elisha Mitchell showing the observatory (south is up/north is down)
Interior plans, drawn 1896 (drawing by Ralph M. Trimble, via UNC)
This observatory was built in 1831-1832 by/for UNC President Joseph Caldwell, but was soon abandoned after Caldwell's death in 1835.
Upon the structure's completion, scientific instruments that Caldwell had purchased during a trip to Europe in 1824 were moved into it.
The building materials used in the structure were very poor; the bricks in the wall soon crumbled, and it became necessary in January 1835 to remove the instruments (likely done by Elisha Mitchell). The building soon fell into decay and was abandoned, and was completely destroyed in a fire in 1838.
A description from Kemp P. Battle's History of the University (1901):
"The building was of bad materials and fell rapidly to decay...After the death of President Caldwell it became necessary to remove the [astronomy instruments Caldwell had purchased in Europe]. In 1838, the building was destroyed by fire (kindled by a student, tradition says). The sound bricks were used to build a kitchen for President Swain
. The site of the old observatory is easily recognized by the brick-bats and by the cedars clustering around the shrunken basement.”
The hill that it was once located on was levelled sometime in the early 20th century.
Note: The following image is probably waaaaay off regarding its accuracy; it was drawn around 60 years after the fact ("Drawn from description furnished by John H. Watson, Esq., Mayor of Chapel Hill, N. C."):