Ratcheugh Observatory is an impressive eighteenth century sham ruin on a crag in Northumberland, enjoying spectacular views of the coast and Aln valley. Designed by Robert Adam around 1784 in memory of the first Duchess of Northumberland, the centrepiece of the ruin is the first floor Observatory, or viewpoint. The rocky hilltop, which has iron age remains, was a favourite picnic spot of the first Duchess and the monument is a prominent landscape feature. The second Duke of Northumberland constructed a cottage for a keeper at one end of the ruin, and the Observatory was used during the Second World War as part of the coastal defences of Britain against invasion. Our condition report identified serious structural defects, which led to the monument being propped to preserve it from collapse; we acted in the re-leading of the observatory roof to ensure the survival of historic plasterwork and joinery; undertook extended negotiations with grant making bodies; and prepared a comprehensive scheme of repair and conservation, which has ensured the survival of this important and unusual historic monument.