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Tresco Map

Like its older brother, the King Charlesʼs Castle on the hill above, Cromwellʼs Castle does not really justify its name.

Itʼs not a castle and it was probably built by the Royalist Governor Sir John Grenville sometime between 1649 and 1651.

It was recorded as a 'new blockhouse' in a Parliamentary Survey of 1652, shortly after they had captured the islands.

Architecturally, however, the tall cylindrical tower is a bit of an oddity, as it looks it should date from the 1550s and there is some evidence that there may have been an earlier fort on this site.