Connecticut Valley Railroad Roundhouse and Turntable Site

Cypress Cemetery is an historic cemetery at 100 College Street in Old Saybrook, Connecticut. Established sometime in the 17th century, and still in active use, it is the town's oldest cemetery, with a wide variety of funerary art dating from the 17th to 21st centuries. The cemetery's oldest portion was listed on the National Register of Historic Places in 2018.

The Black Horse Tavern is a historic building at 175 North Cove Road in Old Saybrook, Connecticut. Built c. 1712 by John Burrows, this 2+1⁄2-story wood-frame structure is one of few early 18th-century buildings still standing in Connecticut, built on land that was among the earliest settled in the area. Now a private residence, it was listed on the National Register of Historic Places in 1978.

The Saybrook Colony was an English colony established in New England in late 1635 at the mouth of the Connecticut River which today is Old Saybrook, Connecticut. Saybrook was founded by John Winthrop, the Younger, son of John Winthrop the Governor of the Massachusetts Bay Colony. Winthrop the Younger was designated Governor by the original settlers, including Colonel George Fenwick and Captain Lion Gardiner. They claimed possession of the land via a deed of conveyance from Robert Rich, 2nd Earl of Warwick. The colony was named in honor of Lords Saye and Brooke, prominent Parliamentarians and holders of the colony's land grants.

The William Tully House, also known as Hartsease or Heartsease, is a historic house at 135 North Cove Road in Old Saybrook, Connecticut. Built about 1750, it is a well-preserved and architecturally unusual example of period architecture. It also has a well-documented history, having association with one of Connecticut's leading physicians of the early 19th century, and an incident in the American Revolutionary War. It was listed on the National Register of Historic Places in 1982.

The North Cove Historic District encompasses a historic waterfront community on North Cove Road in Saybrook, Connecticut. Laid out in the 17th century, the area has housing stock mostly built between 1700 and 1855, a period in which it flourished as a port and shipbuilding community. The district was listed on the National Register of Historic Places in 1994.

Fenwick is a borough in Middlesex County, Connecticut, United States, in the town of Old Saybrook. The borough is part of the Lower Connecticut River Valley Planning Region. The population was 53 at the 2020 census, making it the least populous borough in Connecticut. Most of the borough is included in the Fenwick Historic District, listed on the National Register of Historic Places. In 1995, the district included 66 contributing buildings and one other contributing site.Fenwick is set off from the town center of Old Saybrook by a large cove crossed by a causeway. It is located exactly where the Connecticut River flows into Long Island Sound, and sits on the river's west side. The town has two lighthouses, the Inner and the Outer. The Inner is at the tip of Lynde Point, Fenwick's peninsula, and the Outer is a quarter mile off shore, connected by a rough jetty. The Outer Light is the lighthouse shown on many Connecticut license plates.

The Samuel Eliot House is a historic house at 500 Main Street in Old Saybrook, Connecticut. Probably built in 1737, it is a well-preserved example of Georgian residential architecture, and one of Old Saybrook's older buildings. The house was listed on the National Register of Historic Places in 1972.

The Connecticut River is the longest river in the New England region of the United States, flowing roughly southward for 406 miles (653 km) through four states. It rises 300 yards (270 m) south of the U.S. border with Quebec, Canada, and discharges at Long Island Sound. Its watershed encompasses 11,260 square miles (29,200 km2), covering parts of five U.S. states and one Canadian province, via 148 tributaries, 38 of which are major rivers. It produces 70% of Long Island Sound's fresh water, discharging at 18,400 cubic feet (520 m3) per second.The Connecticut River Valley is home to some of the northeastern United States' most productive farmland, as well as the Hartford–Springfield Knowledge Corridor, a metropolitan region of approximately two million people surrounding Springfield, Massachusetts, and Hartford, Connecticut.

Saybrook Breakwater Lighthouse is a sparkplug lighthouse in Connecticut, United States, at Fenwick Point at the mouth of the Connecticut River near Old Saybrook, Connecticut. It is featured on the state's "Preserve the Sound" license plates. "That outer lighthouse is the symbol of Old Saybrook," town First Selectman Michael Pace said in 2007, when the town was making plans to buy the lighthouse from the federal government.The lighthouse is also known simply as "Breakwater Light" or "Outer Light". It is one of two built off Lynde Point in the nineteenth century. The other lighthouse, known as Lynde Point Light or more commonly as "Inner Light", is 75 years older than this lighthouse. The two lighthouses mark the harbor channel at the mouth of the Connecticut River.

The Gen. William Hart House is a historic house at 350 Main Street in Old Saybrook, Connecticut. Built in 1767 for a politician and colonial militia leader, it is a good example of Georgian residential architecture. The house was listed on the National Register of Historic Places in 1972, and is a contributing property to the Old Saybrook South Green historic district.

The James Pharmacy is a historic building at 2 Pennywise Lane in Old Saybrook, Connecticut. Built in an evolutionary manner beginning about 1820, it is significant as the home and workplace of Anna Louise James (1886–1977), who was the first African-American woman pharmacist in the state, and owned the pharmacy for some time. It is also the birthplace and childhood home of author Ann Petry, who was James' niece. The building was listed on the National Register of Historic Places in 1994, and is a contributing element in the Old Saybrook South Green district.

The Humphrey Pratt Tavern is a historic house at 287 Main Street in Old Saybrook, Connecticut. Built in 1785, it was associated with the locally prominent Pratt family for many years, and served as a tavern and stagecoach stop in the 18th and 19th centuries. It was listed on the National Register of Historic Places in 1976.