Qualla: Castle Down

Castle Down: Introduction

Sat, 23 May 2026 00:00:00 GMT

Photo credit Jowaninpensans, CC BY-SA 4.0. Stand on Castle Down in a westerly gale and the heather lies down sideways. The plants on this 35-metre granite plateau at the northern end of Tresco grow into low waves, with the windward side stripped bare and the leaves and flowers concentrated on the leeward face - a feature ecologists call waved heath. Beneath this carpet of gorse and bell heather lie 66 Bronze Age cairns, the ruins of two Tudor castles built to guard New Grimsby harbour, the spoil heaps of a failed seventeenth-century tin mine, and a deep sea cave called Piper's Hole where in 1993 a husband-and-wife team of cavers found a springtail new to British science. Castle Down is a Site of Special Scientific Interest, part of the Isles of Scilly Area of Outstanding Natural Beauty, and one of the few European sites for a rare lichen called Heterodermia propagulifera. It is also entirely owned by the Duchy of Cornwall.

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Image: Jowaninpensans | CC BY-SA 4.0

Castle Down: The Cairnfield

Sat, 23 May 2026 00:00:00 GMT

Photo credit Andrew Abbott, CC BY-SA 2.0. Castle Down holds 66 cairns dating to the Bronze Age. Most are flat platform cairns - low stone piles built up over a generation or two and then left as monuments rather than active burial places. Just south of the SSSI boundary, an Iron Age field system covers another 3 hectares...

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Image: Andrew Abbott | CC BY-SA 2.0

Castle Down: Two Castles, One Headland

Sat, 23 May 2026 00:00:00 GMT

Photo credit David Lally, CC BY-SA 2.0. Two artillery forts sit on the western side of Castle Down. The older - King Charles's Castle - was built between 1548 and 1551 in the reign of Edward VI, perched too high above New Grimsby harbour for its guns to fire effectively downward. For a brief period it was the principal...

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Image: David Lally | CC BY-SA 2.0

Castle Down: The Tin Mine That Wasn't

Sat, 23 May 2026 00:00:00 GMT

Photo credit Andrew Abbott, CC BY-SA 2.0. In 1652 the Parliamentary Survey of Scilly recorded a row of shallow pits and spoil heaps on Castle Down, following the line of a tin lode. The pits ran 1.8 to 2.4 metres deep with some shafts reaching 7.3 metres, and at the western end of the workings there was an adit - a horiz...

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Image: Andrew Abbott | CC BY-SA 2.0

Castle Down: Piper's Hole

Sat, 23 May 2026 00:00:00 GMT

Photo credit Public domain. On the north coast, where the cliffs drop to the Atlantic, a fissure in the granite leads down into a cave called Piper's Hole. The cave consists of a 20-metre boulder-filled passage that opens into an underground pool. Reaching it requires a scramble down the cliff and then a ca...

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Image: Public domain

Castle Down: Waved Heath and Rare Lichens

Sat, 23 May 2026 00:00:00 GMT

Photo credit Burmesedays, CC BY-SA 3.0. The vegetation on Castle Down is ankle-high. Thin podzolic soils over coarse-grained Hercynian granite, constant salt-laden wind, and almost no shelter combine to prune everything down to a compressed carpet of plants. Western gorse and bell heather dominate, with common bird's-f...

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Image: Burmesedays | CC BY-SA 3.0