Portsmouth Harbor Lighthouse is nestled within Fort Constitution in New Castle, New Hampshire.
Overlooking the entrance to Portsmouth Harbor and the Piscataqua River, this historic beacon has guided vessels safely since the 18th century, marking it as a significant landmark in New England’s coastal history.
History of Portsmouth Harbor Lighthouse
Established in 1771, Portsmouth Harbor Lighthouse was the tenth of eleven light stations built before the American Revolution. The original structure was a wooden tower with an iron lantern and copper roof, illuminated by three copper oil lamps.
In 1804, a new 80-foot octagonal wooden tower replaced the original, situated approximately 100 yards east of the initial site. This tower was later shortened to 55 feet in 1851, following the establishment of the nearby Whaleback Lighthouse.
A significant upgrade occurred in 1854 with the installation of a fourth-order Fresnel lens, enhancing the lighthouse’s visibility. The current 48-foot cast-iron, brick-lined tower was erected in 1878 on the same foundation as its predecessor. The lighthouse was electrified in 1925, automated in 1960, and added to the National Register of Historic Places in 2009.
Throughout its history, the lighthouse has undergone various modifications to improve its functionality and durability.
Portsmouth Harbor Lighthouse Architecture and Design
The existing lighthouse is a conical, cast-iron tower lined with brick, standing 48 feet tall. Originally painted white when erected in 1878, the tower was changed to brown in 1887 before being repainted white again in 1902, a color it retains today. It features a black lantern housing the light apparatus.
The lighthouse’s design reflects the typical architectural style of late 19th-century American lighthouses, combining both functionality and aesthetic appeal. A fourth-order Fresnel lens (not the original 1854 lens, but a replacement of the same order) remains in use, producing a fixed green light visible up to 12 nautical miles. The light has been fixed green since 1941.
Location and Surroundings
Situated on the northeastern corner of New Castle Island, Portsmouth Harbor Lighthouse marks the entrance to Portsmouth Harbor, guiding maritime traffic along the Piscataqua River and the Atlantic Ocean. The lighthouse is encompassed by Fort Constitution, a historic military fortification with origins dating back to the early 17th century.
The area offers picturesque views of the harbor, nearby Whaleback Lighthouse, and the surrounding seascape, making it a popular spot for history enthusiasts and sightseers alike.
Visiting Portsmouth Harbor Lighthouse
Current Status (as of 2026): Portsmouth Harbor Lighthouse is closed to the public. The wooden footbridge that provided access from Fort Constitution was destroyed in a December 2022 storm, and back-to-back January 2024 storms caused additional damage to the lighthouse base and oil house. The Friends of Portsmouth Harbor Lighthouses launched a capital campaign in 2025 to fund the rebuild. Tours will resume once construction is complete.
Best Viewing Locations
While the lighthouse itself is inaccessible, you can still enjoy excellent views from several public spots:
- Great Island Common, a town park on Route 1B in New Castle, offers the best land-based view of the lighthouse, plus picnic areas, walking paths, and views of the harbor.
- Fort Constitution Historic Site remains open to the public during daylight hours. While you cannot reach the lighthouse from the fort grounds, you can see it from a distance and explore the historic fortification dating to the early 17th century.
- The grounds near the U.S. Coast Guard Station gate in New Castle provide a closer perspective.
Lighthouse Cruises
The most rewarding way to see Portsmouth Harbor Lighthouse up close is by water. Several operators run seasonal lighthouse cruises:
- Friends of Portsmouth Harbor Lighthouses partners with the M/V Granite State out of Rye Harbor State Marina for sunset lighthouse cruises in June and an annual five-lighthouse cruise in September that passes White Island Light, Boon Island Light, Cape Neddick (Nubble) Light, Whaleback Light, and Portsmouth Harbor Light. Tickets sell out quickly. Visit the Friends of Portsmouth Harbor Lighthouses for current schedules.
- Portsmouth Harbor Cruises and other local operators run narrated harbor tours from Portsmouth that pass close to both Portsmouth Harbor and Whaleback lighthouses.
Getting to Great Island Common
From Interstate 95, take Exit 5 (Portsmouth Circle) and follow signs for Route 1 Bypass South. After approximately two miles, turn left onto Elwyn Road, following it for about 1.4 miles to a small traffic circle. Exit onto Route 1A North (Sagamore Road) and proceed for 0.4 miles to the intersection with Route 1B (Wentworth Road). Turn right onto Route 1B, cross a bridge, and continue past the Wentworth-by-the-Sea Hotel. Great Island Common is on the right.
Plan Your Visit
Even with the lighthouse closed to climbing tours, Portsmouth Harbor Lighthouse remains one of New England’s most photographed and historically significant beacons. Pair a visit to Great Island Common with a stop at Fort Constitution, lunch in nearby Portsmouth, and a sunset lighthouse cruise for a full day of maritime history. Whether you’re a history enthusiast, photographer, or casual traveler, this corner of New Hampshire’s seacoast rewards the trip.