The Equatorial Observatory, Penllergare

Observatory and laboratory, the observatory a cylindrical tower of tolled squared stone with C20 metal-clad cylinder above, the laboratory a single-storey neo-Jacobean structure in yellow patent blocks, larger than conventional bricks. Observatory is windowless cylinder with some small square recess close to foot of the wall and an ogee cornice, eroded and patched in cement. The C20 top part has cylinder of metal sheets. The laboratory is a single room with slate roof behind parapet. Stone plinth, terracotta-block walls, the parapet with centre shaped neo-Jacobean gables rebuilt in imitation blocks in 1981. One window to N with C20 cross-window, possibly in former door opening. Surround is chamfered with terracotta block voussoirs. S side has similar window to right and door to centre, both with similar chamfered surrounds and voussoirs. C20 door and window.

Interior of observatory inaccessible, laboratory is single room with terracotta block walls and fireplace on right end wall.