| The Giant's Castle | |
| Map Type: | Isles of Scilly |
| Map Size: | 240px |
| Coordinates: | 49.9117°N -6.2853°W |
| Gbgridref: | SV 925 101 |
| Area: | 0.4ha |
| Designation1: | Scheduled monument |
| Designation1 Number: | 1011935 |
| Designation1 Date: | 7 October 1976 |
The Giant's Castle is a promontory fort of the Iron Age, on St Mary's, Isles of Scilly, England. It is a scheduled monument.
The fort is situated in the south-east of St Mary's, near St Mary's Airport and on the edge of Salakee Down. The rocky promontory, area 0.4ha, is defended by sea cliffs, 15to high, on the east, south and south-west sides. To the north there are three banks and ditches, 8to apart; these occupy most of the steep northern slope linking the promontory to the mainland. The castle, on almost level ground within the promontory, has an internal area of about 25by.[1]
During the Second World War, a practice firing target for military aircraft was made in the western end of the outermost rampart. This survives as an unroofed rectangular structure up to high. Fragments of early Iron Age pottery were recovered from cuttings made by the army.[1]