Holy Apostles College and Seminary

The Main Street Historic District in Cromwell, Connecticut is roughly bounded by Nooks Hill Rd., Prospect Hill Rd., Wall and West Sts. and New Ln., and Stevens Ln. and Main St. It includes two town greens (Valour Green and Memorial Green), historic homes and the Cromwell Historical Society. The historic district is primarily linear and starts from "Patriots Corner" (a grassy area at the corner of Main and Wall Streets with several memorials) and runs north along Main Street (Route 99) past the Memorial Green at Wall Street. Towards the northern end, the district widens to encompass both Main Street and Prospect Hill Road until about Nooks Hill Road, including the Valour Green. The district comprises 66 contributing buildings and structures and has an area of 130 acres (53 ha). The district is notable in capturing the transformation of a rural 18th-century village center into a 20th-century town, with representative architecture from every major architectural style seen between 1750 and 1935. The district was listed on the National Register of Historic Places in 1985.Cromwell was settled in the 17th century, and remained predominantly agricultural in character well into the 19th century. It had a small but locally important port on the Connecticut River, which declined in the 19th century, and Main Street afterward became the principal economic and civic area of the town. Main Street was part of a major turnpike route, connecting Hartford and Old Saybrook, and is where the town's early civic buildings were located.

Cromwell High School is the town high school of Cromwell, Connecticut.

Cromwell is a town in Middlesex County, Connecticut, United States located in the middle of the state. The town is part of the Lower Connecticut River Valley Planning Region. The population was 14,225 at the 2020 census.The town was named after a shipping boat that traveled along the Connecticut River, which runs along Cromwell. The ship was named after Oliver Cromwell, Lord Protector of the Commonwealth of England. Other theories are that the town was named after the 1776 warship Oliver Cromwell, or named directly after the Lord Protector Cromwell.The Roman Catholic Padre Pio Foundation of America is located in Cromwell. The Evangelical Covenant Church's regional East Coast Conference offices are located in Cromwell.

The Middletown Upper Houses Historic District, also known as the Upper Houses River Port, encompasses the historic early nucleus of Cromwell, Connecticut. Sandwiched between Main Street and the Connecticut River, this area was set off from neighboring Middletown in 1851. It is visually dominated by residential structures built before 1810. The area grew as a significant river port and shipbuilding center until the mid-19th century. The district was listed on the National Register of Historic Places in 1979.

River Highlands State Park is a public recreation area located on the west bank of the Connecticut River in the town of Cromwell, Connecticut. The 177-acre (72 ha) state park is managed by Connecticut Department of Energy and Environmental Protection.

The Coginchaug River in Connecticut, with a watershed including 39 sq mi of forests, pastures, farmland, industrial, and commercial areas, is the main tributary of the Mattabesset River. It is 16.1 mi long, and the river flows northwards from a point approximately 1.8 mi south of the Durham line in Guilford, Connecticut, into Durham and then Middlefield, meeting the Mattabesset in Middletown, about 0.8 miles (1.3 km) upstream of the Connecticut River. The name "Coginchaug" comes from a local Native American name for the Durham area and it was the original name for the town. It has been said to mean "The Great Swamp", and is a reference to the meadows found in the central part of town. In 2006, the Coginchaug was among Connecticut's 85 waterways cited to be of "lower quality", in view of the elevated levels of bacteria, including E. coli. Currently, efforts are being made by the Natural Resources Conservation Service of the United States Department of Agriculture to reduce the number of bacteria introduced into the river from untreated sewage, sanitary sewer overflow, agricultural runoff, leaking septic tanks, etc.

The White-Overton-Callander House is a historic house museum at 492 Main Street in Portland, Connecticut. Built in the 1710s, it is one of the community's oldest surviving buildings, built by Nathaniel White, one of the first proprietors of Middletown. Owned since 1997 by the local historical society, it is open for tours on some Sundays. It was listed on the National Register of Historic Places in 2013.

The Indian Hill Avenue Historic District encompasses an 18th-century colonial shipbuilding village, overlaid on a historic and prehistoric Native American settlement, in Portland, Connecticut. Extending along Indian Hill Avenue north of Portland, the district includes a collection of 18th and early 19th-century buildings, and extensive archaeological evidence of Native American occupation (some supported by colonial-era and later documentation). The district was listed on the National Register of Historic Places in 1983.

The Sage-Kirby House is a historic house at 93 Shunpike Road in Cromwell, Connecticut. Built sometime between 1811 and 1815, it is one of four Federal-period brick houses in the town, and the only one of these with a central chimney. The house was listed on the National Register of Historic Places on April 29, 1982.

The Portland Brownstone Quarries are a set of historic quarries in Portland, Connecticut. The brownstone mined from these quarries was an important source for construction in the latter half of the 19th century. The stone from these quarries was used in a number of landmark buildings in Chicago, Boston, New York City, Philadelphia, Baltimore, Washington, D.C., New Haven, Connecticut, and Hartford. The site was listed as a National Historic Landmark, which also placed it on the National Register of Historic Places, on May 16, 2000.

The Mattabesset River as delineated on present-day maps flows out of Harts Ponds in the town of Berlin and travels 16.1 miles (25.9 km) east to the Connecticut River, passing Kensington and later forming the boundary between Middletown and Cromwell.Further south, the Coginchaug River (or "winding meadow") flows from an upland meadow in Durham, northwards to the Mattabesset just upstream of that river's junction with the Connecticut. This river was the route to the portage place, located near Palmer Field, just below Sowheag's main stronghold at Indian Hill. Since it was the old western boundary of the incorporated City of Middletown, it was also called the West River, and also, for no known reasons, it was given other names, including the Sebethe River and the Arrawanna River. Presumably the word Mattabeseck was never considered properly euphonious, and various local individuals tried to improve on the name poetically.

Portland is a census-designated place (CDP) comprising the primary village and adjacent residential land in the town of Portland, Middlesex County, Connecticut, United States. It is in the southwest part of the town, bordered to the west and south by the Connecticut River, which forms the border with Cromwell to the west and Middletown to the south. The Portland CDP extends north along Main Street (Connecticut Route 17A) to its junction with Gospel Lane (Connecticut Route 17) at Fogelmarks Corners, and the eastern extent of the CDP is at Rose Hill Road and Collins Hill Road. The CDP includes the neighborhood of Gildersleeve in the north. As of the 2020 census, the CDP had a population of 5,813, out of 9,384 in the entire town of Portland.