When is an island not an island? In the case of popular summertime recreation destination Castle Island in South Boston, it’s when it used to be an island. Castle Island, an attraction on the 39-mile Boston HarborWalk footpath (stretching along nearly the entire waterfront), has a long history as both an island and a peninsula.
Originally detached from the mainland, Castle Island was connected to it by a concrete causeway in 1928. The 22-acre state-run park is dominated by Fort Independence, a military structure built between 1834 and 1851 that is the eighth such edifice to occupy this strategic locale near the entrance to Boston Harbor. In fact, the spot where the pentagonal Fort Independence stands has hosted fortifications going back to 1634 and is one of the oldest fortified military sites in North America. Although the exact origin of Castle Island’s name is unknown, one of Fort Independence’s predecessors was the British fort known as Castle Williams, which was burned by the Brits as they retreated from Boston in 1776. Famous names who have served here over the years include Paul Revere and Edgar Allan Poe, whose story “The Cask of Amontillado” was allegedly inspired by legends he heard about a dispute between two officers who served there a decade prior to Poe’s five-month tour of duty in 1827. Fort Independence is a National Historic Landmark and both the fort and Castle Island are on the National Register of Historic Places.
Today, visitors can explore the granite-lined halls of Fort Independence on guided tours hosted by the Castle Island Association that run on weekends and holidays until Columbus Day. Another feature of the “island” is Pleasure Bay, an enclosed lagoon and beach area frequented by sun worshippers. There’s even a fishing pier for anglers. Harbor views, sea breezes, beaches and history—with a combination like that, it’s no wonder this park has continued to maintain its allure over the years.

Photo: 1938/ Courtesy of Boston Public Library