The Royal Observatory was preceded on the same site by a 15th century watchtower and hunting lodge, considerably developed before its ruins were cleared for the Observatory to be built on the same foundations. This building, in the picturesque Jacobean style more in tune with the vanished palace than its classical successors, is mostly associated with its role as the centre of astronomical measurement, but it also forms an important part of the composition of the group.
Upon the restoration of Charles II, John Webb was engaged to construct a new palace building on the site of the former one as this was slowly cleared away, his only completed structure being to the west of the axis of the Queen’s House and maintaining the view of this building from the river. Webb adopted the grand style for this single block with monumental Portland stone facades and a giant Corinthian order for its entrance. The river elevation was even grander with, eventually, doubled porticos surmounting engaged columns stretching along the whole façade.