The Observatory

The Observatory is a Grade I listed gazebo and eyecatcher built in the late 18th century by Robert Adam for the Duke of Northumberland, with additions made around 1850. It is constructed of rough-faced stone with ashlar dressings and features towers with flat roofs, except for the south tower, which has a pent roof covered in Welsh slates. The structure is set on the crest of a whinstone escarpment, offering commanding views to the west over Alnwick and to the east towards the sea, and is designed in a castellated Gothick style.

The west elevation has a chamfered plinth. The main tower, located near the left end, has an open base with a segmental hollow-chamfered arch flanked by semi-octagonal buttresses topped with pyramids. At the first-floor level, there are three 12-pane sash windows with intersecting heads under round arches, set in a recess with a corbelled top. A moulded string course runs below the embattled parapet. This first-floor band continues along the flanking walls, which feature smaller round arches leading to taller semicircular turrets with various shaped loops. The right lower wall has a large semicircular bow and a square turret with quatrefoil and cruciform loops, connecting to the rectangular south tower. The south tower has a central bow with ground- and first-floor windows featuring 4-centred arches (which are boarded over) and a band on corbels below an irregular parapet, with a lower pent part to the far right.

The rear elevation of the main tower mirrors the front. A turret to the left has a boarded door under a round arch leading to a newel stair, from which a short wall walk leads to a balcony on the left return of the tower, featuring a central part-glazed door. The south tower has a quatrefoil loop at the rear and boarded window openings in the returns, under 4-centred or pointed arches.

Inside, the observatory in the main tower features a fluted dado rail and a fan tracery cornice.