If it's called Castle Island, why can I drive there?

This is one of Boston's most perplexing questions. Well, at one time Castle Island was, indeed, an island out in Boston Harbor. (Henry Pelham's map from the Revolutionary War era shows the island sitting off Dorchester Neck, which is now South Boston.) Just as much of present-day Boston was created by filling in parts of Boston Harbor and the Charles River, Castle Island was eventually connected to the mainland in the 1930s after successful landmaking efforts. Deer Island and Nut Island, part of the Boston Harbor Islands National Recreation Area, also retain their monikers even though they are also now peninsulas.

Castle Island gained its name as a result of the fortifications that were built there by the Puritans and John Winthrop as early as 1634, making it the oldest continually fortified site in the country. The fort would eventually be called Fort William after the king of England. (You'll notice on Pelham's map that it's called Fort William and Mary.) After the British were driven out of Boston in March 1776, the fort fell into the patriots' hands. President John Adams rededicated the fort as Fort Independence and today it is on the National Historic Register of Places. During the summer, tours of the fort are available each weekend day between 12 and 3, and the fort is open for twilight walks between 7 p.m. and dusk.

Today, Castle Island is a popular recreation area for the city residents. And in a real rarity in Boston, there are hundreds of free parking spots. You'll find people sitting in their cars enjoying the view or eating lunch, older men from the neighborhood talking about the Red Sox or their retirement investments, children on scooters and bikes, fishermen casting their lines. There is a sailing center and lifeguarded beach on Pleasure Bay, which is encircled by a long causeway. The causeway looks like a bygone remnant from the days when city residents would spend the afternoon strolling on the promenade and escaping the heat of their crowded neighborhoods. That's for good reason, since the landscape design for Castle Island and adjacent Marine Park is based on the original plans of Frederick Law Olmsted, who wanted this land to be the end of his Emerald Necklace and a place where weary workers could enjoy the salubrious salt breezes of the harbor.

These days, the smell of the salt water combines with the scent of fried food coming from Sullivan's, a South Boston institution. It will make you glad you can drive right up to Castle Island.