The 16th century Old Blockhouse is located at the southern end of Old Grimsby harbour on Tresco. It was built in the reign of Henry VIII as part of a series of coastal defences to protect against invasion from the French. Select ratingGive The Old Blockhouse 1/5Give The Old Blockhouse 2/5Give The Old Blockhouse 3/5Give The Old Blockhouse 4/5Give The Old Blockhouse 5/5 No votes yet Rate Location Old Grimsby Tresco Isles of Scilly TR25 0QW Isles of Scilly Go to website » 0870 333 1181 Attractions near The Old Blockhouse King Charles Castle Harrys Walls Cromwell's Castle Garrison Walls Tresco Abbey Gardens