South Boston projects farther into the harbor than any other part of Boston except Logan Airport, and the views of the Harbor Islands from along Day Boulevard or Castle Island are expansive. At L Street and Day Boulevard is the L Street Beach, where an intrepid group called the L Street Brownies swims year-round, including a celebratory dip in the icy Atlantic every New Year's Day. Castle Island Park is no longer on an island, but Fort Independence, when it was built here in 1801, was separated from the mainland by water. The circular walk from the fort around Pleasure Bay, delightful on a warm summer day, has a stunning view of the city's skyline late at night. If you get peckish, stop by Sullivan's (open February through November), a Castle Island institution for more than 60 years, for a hot dog and fries. To get here by the T, take the Red Line to Broadway Station. Just outside the station, catch Bus 9 or 11 going east on Broadway, which takes you to within a block of the waterfront. From the waterfront park you can walk the loop, via piers, around the island.