 It is one of a number of prominent follies built on the skylines around Alnwick; other include the 1781 Brizlee Tower, another creation of the Duke; Jenny's Lantern on the Bolton estate, and Crawley Tower on the Shawdon estate, all dating to the late 18th-century.The Observatory incorporates a small cottage, a later c.1850 addition.The Observatory is a Grade 1 listed building.