 Ratcheugh Observatory is located on Ratcheugh Crag, a local whinstone high-point above a foreground of fields at or lower elevations, situated east-north-east of Alnwick and west-south-west of Longhoughton; inland from the coast at Boulmer, in north Northumberland.The Observatory at Ratcheugh is a screen-wall built at the crag edge, incorporated into which are a number of turrets or towers; and having towards its northern extent a square-plan viewing tower built on open hollow-chamfered arches.The tower has a single enclosed room, each wall having three large round-arched windows affording commanding views to the north-east, north-west, south-east and south-west.