Longfellow Bridge

The Longfellow Bridge, also known to locals as the "Salt-and-Pepper Bridge" or the "Salt-and-Pepper-Shaker Bridge" due to the shape of its central towers, carries Route 3 and the Massachusetts Bay Transportation Authority's Red Line across the Charles River to connect Boston's Beacon Hill neighborhood with the Kendall Square area of Cambridge, Massachusetts.

Longfellow Bridge is a combination railway and highway bridge. It is 105 feet (32 m) feet wide, 1,767 feet 6 inches (538.73 m) long between abutments, and nearly one-half mile in length, including abutments and approaches. It consists of eleven steel arch spans supported on ten masonry piers and two massive abutments. The arches vary in length from 101 feet 6 inches (30.94 m) at the abutments to 188 feet 6 inches (57.45 m) at the center, and in rise from 8 feet 6 inches (2.59 m) to 26 feet 6 inches (8.08 m). Headroom under the central arch is 26 feet (7.9 m) at mean high water. Its two large central piers, 188 feet (57 m) long and 53 feet 6 inches (16.31 m) wide, feature carved, ornamental stone towers that provide stairway access to pedestrian passageways beneath the bridge. Its sidewalks were originally both 10 feet (3.0 m) wide, but now, for unknown reasons, the upstream sidewalks are narrower than the downstream ones.

The bridge falls under the jurisdiction and oversight of Massachusetts Department of Transportation. The bridge carries approximately 28,600 cars and 90,000 mass-transit passengers every weekday. A portion of the elevated Charles/Massachusetts General Hospital train station lies at the eastern end of the bridge.