'A perennial Kew' - home to 20,000 exotic plants with species from 80 countries, ranging from Brazil to New Zealand and Burma to South Africa
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.
Remains of castle built for coastal defence on the north side of Tresco
16th-century fort built over St Mary's Pool harbour, but never finished
Extensive defensive walls and earthworks dating back to the 16th century
17th-century round tower positioned on a rocky promontory guarding the anchorage between Bryher and Tresco.