Thankful Arnold House Museum

The James Hazelton House, also known as the Hazelton-Hayden House, is a historic house at 23 Hayden Hill Road in Haddam, Connecticut. With a construction history dating to about 1720, it is one of the town's oldest buildings, with a long history of ownership by a single prominent local family. The house was listed on the National Register of Historic Places in 1988, and is a contributing property in the Haddam Center Historic District.

The Haddam Center Historic District is a 267-acre (108 ha) historic district encompassing the institutional and residential center of the town of Haddam, Connecticut that was listed on the National Register of Historic Places in 1989 as a result of efforts by the Haddam Historical Society.The town center of Haddam was first laid out in 1662, when land was set aside for a colonial meeting house, a minister's house, and land for the minister. The town's early growth was slow, because the terrain was not very suitable for agriculture. After American independence, the town began to grow more substantially, buoyed by construction of the Middlesex Turnpike along what are now CT 154 and Walkley Hill Road. The town center grew as a stop on the turnpike, and also benefited from traffic along the Connecticut River, which formed its eastern boundary. The introduction of steamship and railroad traffic beginning around 1850 led to a decline in the town's fortunes.The district is basically linear in nature, extending about 2.5 miles (4.0 km) along CT 154 and Walkley Hill Road. It boasts a fine collection of Federal period residential architecture, and a number of institutional and civic buildings constructed in the mid-19th century out of locally quarried granite. It includes the James Hazelton House, at 23 Hayden Hill Rd., which is separately NRHP-listed, as well as the Brainerd Memorial Library.

Haddam Meadows State Park is a public recreation area occupying 175 acres (71 ha) on the west bank of the Connecticut River in the town of Haddam, Connecticut. The state park offers picnicking, fishing, and a boat launch. Park trails lend access to a diversity of riverside landscapes: marsh, beach, sand bar, fern growths, meadow lands, and hardwood forest. The park was established through the donation of land in 1944 by the Edward W. Hazen Foundation. It is managed by the Connecticut Department of Energy and Environmental Protection.

Haddam Island State Park is an undeveloped 14-acre (5.7 ha) island in the lower Connecticut River in the town of Haddam, Connecticut, in the United States. Originally used by the Wangunk tribe, the island was reserved for their use as part of a 150-square-mile (390 km2) land sale to English colonists in May 1662. In the 19th century, the island was used for fishing and farming. The early 20th century saw it as a place of public recreation, and the State of Connecticut purchased the island and made it a state park in 1944. The park is only accessible by boat, and recommended activities are boating, fishing, and birdwatching.

Connecticut Yankee Nuclear Power Plant (CY) was a nuclear power plant located in Haddam Neck, Connecticut. The power plant is on the Connecticut River near the East Haddam Swing Bridge. The plant was commissioned in 1968, ceased electricity production in 1996, and was decommissioned by 2004. The reason for the closure was because operation of the nuclear power station was no longer cost effective. The plant had a capacity of 582MW. Demolition of the containment dome was completed the week of July 17, 2006. Kenneth Nichols, the deputy to Leslie Groves on the Manhattan Project, was a consultant for the Connecticut Yankee and Yankee Rowe nuclear power plants. He said that while the plants were considered "experimental" and were not expected to be competitive with coal and oil, they "became competitive because of inflation … and the large increase in price of coal and oil." The Connecticut Yankee plant was estimated to cost $100 million.

The Salmon River is formed at the confluence of the Blackledge and Jeremy rivers about one mile west of North Westchester, Connecticut. It drains 96,000 acres and courses for 10.4 miles (16.7 km) to Salmon Cove near Moodus where it flows into the Connecticut River. The Salmon River is probably the largest stream and watershed whose sources and mouth are entirely within the limits of Connecticut.There is a popular paddling route along the Salmon River varying in difficulty from quickwater to Class II whitewater. It begins along River Road about 1/10 of a mile south of the river's formation and continues for about 7 miles to the flatwater of Salmon Cove. The Salmon River's substantial drop in elevation over its course provided considerable water power to the textile mills in Moodus during the 19th and early 20th centuries.

George Dudley Seymour State Park is a public recreation area occupying 222 acres (90 ha) on the east bank of the Connecticut River in the town of Haddam, Connecticut. Hurd State Park abuts the park to the north. The park bears the name of George Dudley Seymour (1859-1945), whose philanthropic efforts enabled the state to purchase land for this and several other Connecticut state parks. It is managed by the Connecticut Department of Energy and Environmental Protection.

Middlesex County is a county in the south central part of the U.S. state of Connecticut. As of the 2020 census, the population was 164,245. The county was created in May 1785 from portions of Hartford County and New London County. Middlesex County is included in the Hartford-East Hartford-Middletown metropolitan statistical area known as Greater Hartford. As with all eight of Connecticut's counties, there is now no county government and no county seat. In Connecticut, towns are responsible for all local government activities, including local police, fire and rescue, snow removal, and schools. In a few cases, neighboring towns will share certain resources, e.g. water, gas, etc. On June 6, 2022, the U.S. Census Bureau formally recognized Connecticut's nine councils of governments as county equivalents instead of the state's eight counties. Connecticut's county governments were disbanded in 1960, and the councils of governments took over some of the local governmental functions. Connecticut's eight historical counties continue to exist in name only, and are no longer considered for statistical purposes.

Higganum Reservoir is a 31-acre (13 ha) human-made body of water impounding Ponset Brook in the town of Haddam, Connecticut, United States. It is the primary feature of Higganum Reservoir State Park. Formed by construction of an earth dam in 1868, the reservoir was built to provide water power for the Higganum Manufacturing Company, a maker of plows and other farm equipment. Later known as Clark Cutaway Harrow, the company produced a line that included 400 types of plows, disk harrows, cider presses, hay spreaders, and carriage jacks. The reservoir's original dam had a maximum height of 48 feet and a total length of embankment (including the spillway) of approximately 875 feet. It was reconstructed by the state in 2003. The dam is located at the reservoir's north end; a boat launch maintained by the state is found at its south end.

Higganum is a village and census-designated place (CDP) in the town of Haddam, a part of Middlesex County, Connecticut, United States. The population was 2,089 at the 2020 census.

Higganum Reservoir State Park is a public recreation area occupying 147 acres (59 ha) on the banks of Higganum Reservoir in the town of Haddam, Connecticut. The state park offers fishing, hiking, hunting, and a launch area for car-top boating. It entered the state rolls as a 75-acre state park in the 1955 edition of the Connecticut Register and Manual.

Machimoodus State Park is a public recreation area located on the Salmon River near the village of Moodus in the town of East Haddam, Connecticut. The state park is bordered by Sunrise State Park to the north and by the Salmon River and Salmon Cove to the west and south. The park is managed by the Connecticut Department of Energy and Environmental Protection.