Boston's Urban Gem Is A Hidden Peninsula With Nature Walks, Beaches, And A Once-Thriving Military Fort

Boston Harbor is dotted with several historic forts. They were built on peninsulas and islands to first protect the new British colony and then the newly formed United States from being invaded by ships. Castle Island was the first site to be fortified and the fort constructed there was later named Fort Independence. Though it's no longer an active military base, or even an island for that matter, it's still a fascinating spot. You'll find beaches and trails surrounding the historic park.

After Boston was founded in 1630, the city's harbor became a vital port for fishing and naval fleets. Castle Island, a 22-acre island overlooking Dorchester Bay in South Boston, was immediately selected for a protective fort by the Massachusetts Bay Colony's governor. The first structure was constructed in 1634, originally named Castle William in honor of England's King William III. It was rebuilt numerous times in the following century. Then, in 1776, the British destroyed their fort while fleeing the city. It was renamed Fort Independence in 1799.

Americans then used Fort Independence for a marine hospital and prison and became a training site during the War of 1812 through World War II. After the fort was decommissioned in 1890, the United States government gave Massachusetts control of the surrounding property, and in 1962, the fort as well. It's all now part of a state park that includes Castle Island and Pleasure Bay (and their beaches), M Street Beach, and Carson Beach. It's also an under-the-radar spot in Boston, a popular East Coast city known for its history and sporty appeal.

A concrete causeway, which turned Castle Island into a peninsula and attached it to the rest of South Boston, was built in 1928. When you arrive at the historic site, you can start by touring Fort Independence to learn about its history, five bastions, reinforced metal doors, and cannons. You'll explore the ramparts, see exhibits in the Model Room, and take in gorgeous Boston views along the way. Volunteers with the Castle Island Association offer free afternoon tours from Memorial Day through Labor Day, as well as Twilight Viewing Thursday evenings.

After touring the inside of the fort, you can head outside to wander around its grounds. There are two trails within the state park. The first trail, the 0.79-mile Castle Island Loop, circles Fort Independence. It's a flat, paved trail used by bikers, runners, walkers, and dog walkers with a bathroom and playground along the way. Then the Pleasure Bay Loop is a 1.84-mile path that rings Pleasure Bay. You'll pass sandy Pleasure Bay Beach, 225-acre Marine Park, and the Head Island viewpoint on this edge-of-the-water walkway.

If you have enough time, you can also combine the two loops on the Boston Harbor and Castle Island trail. This turns the path into a longer, 2.2-mile loop that circles Pleasure Bay and the eastern edge of Castle Island. "In typical Boston fashion, this spot integrates history with seaside recreation," according to one AllTrails user.

While following the trails, you might notice sandy beaches facing the calm waters of Pleasure Bay. Castle Island Beach is small, situated on both sides of the nonprofit Harry McDonough Sailing Center,and Pleasure Bay Beach, which has lifeguards watching the water during the summer is the larger of the two just across the bay. It's the most popular spot to go for a swim. The shoreline continues along Day Boulevard with M Street Beach and Carson Beach, forming a continuous stretch of parkland and beaches.

There's no cost to visit Castle Island or Fort Independence, which are open all year from sunrise to sunset. If you're hungry after exploring the island, be sure to stop at Sullivan's, a casual, order-at-the-counter spot that's been serving seafood and ice cream seasonally since 1951.

Since Castle Island is in South Boston, it's an easy destination to reach. Flights from all around the world land at Boston Logan International Airport (BOS), which has a lounge with mouth-watering lobster rolls and craft cocktails. From New England's largest airport, it's only a five-mile drive to the south, which includes tolls. If you plan on taking the T or bus, be prepared for an hour ride with multiple connections. Then after Castle Island, you can see some of the islands in Boston Harbor Islands National and State Park, an idyllic Massachusetts oasis for outdoor recreation and harbor views. They're just a short ferry ride away from Long Wharf, a historic pier on the coast in the center of the city.