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Notes in italics from Oxfordshire by Jennifer Sherwood and Nikolaus Pevsner (1974)
Yale University Press, New Haven and London.

Built 1772-94 with funds from the Radcliffe Trustees, the building functioned as an observatory until 1934. It is now part of Green Templeton College (GTC), University of Oxford.
It was begun to the design of Henry Keene in 1772, but after his death completed in 1794 to a different design by James Wyatt. ... It is not at all what one expects an observatory to look like. It is a broad and high tower and has no dome. ... The whole S front is of fifteen bays, but ten of them are one-storey attachments. The centre then is of five with a canted middle part against which is the grand doorway. Fluted columns, a fluted frieze, and a pediment. the wings have arched niches alternating with windows ...

The first floor is treated as the piano nobile. It has pilasters, Ionic, unfluted, and pairs of them at the angles, above the windows reliefs of the signs of the Zodiac (by Rossi, made of Coade stone), and a top balustrade. But then Wyatt by a stroke of genius decided to put on top a Wyatt version of the Tower of the Winds. He continued the canting which, as usual with canted bays, has a long front side and two short diagonal sides. So his Tower of the Winds is not a regular octagon, but a strongly canted square, as it were. The main sides have large tripartite windows with columns and a pediment, the short sides windows, and on the whole are the reliefs of the Winds with their Greek names. They are by Bacon, carved in 1792-4 ...

The wings have at their ends each an overarched Venetian window and paterae l. and r. The r. wing is continued by a quadrant link to connect the observatory with the astronomer's house, a three-bay-by-three-bay, quite plain ashlar house. The N elevation of the observatory ... is a semi-circle in plan. The ground floor is plain ... and above is the same order of pilasters as on the S side, but between them are large tripartite windows alternating with simple niches. Above these the signs of the Zodiac ...