Hurst Castle is a strategic Tudor fortress built by Henry VIII between 1541 and 1544 on a shingle spit in Hampshire, England, commanding the western entrance to the Solent waterway. Originally constructed with a central keep and three bastions equipped with significant artillery, the castle played a crucial defensive role during the Tudor period and famously detained King Charles I during the English Civil War. The fortress remained in continuous military use for over 400 years until 1956, with later 19th and 20th-century strengthening adding layers of military heritage. Visitors reach the castle via scenic ferry or a 2-mile coastal walk and can explore multiple chambers spanning centuries of English naval and military history.