Sandsfoot castle was built in Wyke Regis on the north side of Portland Harbour by order of Henry VIII, fearful of attacks by Spanish and French forces. It was built at the same time as Portland Castle on the southern point of the bay and was completed in 1539. It is said that much of the stone for the castle came from the dissolved abbey at Blandon near Wool.
During the English civil war it was held by the Royalists until 1644, when following a siege it was captured by the Parliamentarians, who used it as a storehouse. It continued in this role until around 1691, when coastal erosion was threatening to undermine the cliff on which the castle stands. This was addressed by the building of the Portland breakwater in 1849, but by this time the castle was in a dangerous state and had been abandoned.
It was purchased by Weymouth Council in 1902 for the sum of £150 and Tudor gardens were laid out on the adjoining land and a public park created. It was not until 2009-2010 that in a joint project with a local community trust that funds became available to carry out the works needed to allow public access to the castle buildings.