Union Green, located within the Union Green National Register District, is a small wedge of publicly-owned land at the north end of a 5.3 acre triangle bounded by Town Hall Road, Buckley Highway and Kinney Hollow Road. This grassy northeast tip is almost level and lacks mature trees in contrast to the larger, privately-owned, densely-wooded portion known as Union Grove that extends up and over a rocky knoll.

The Old Town Hall (now a historical society museum) and a small shed to the south of it dominate the green. A narrow asphalt drive passes between the Old Town Hall and the shed.

No curbs separate the green from the bordering streets. The few trees planted on the green - six young, randomly placed crabapple trees and a small oak tree to the east of the Old Town Hall - leave the green open to view. As a result, many of the buildings near the green are visible, particularly since most of the roads rise in elevation as they move away from the green. The most dramatically sited building is the Congregational Church which stands on a knoll overlooking the small green.

The important institutions of the community's life including the former town hall, library, Congregational Church, the Union School and former district school, and cemetery are widely spaced around the green and Union Grove are located near it. Because Union lacked commerce and trade that attracted people to the town, only two houses are located at Union Green. The oldest, built by Ezra Horton in 1759, has two barns to the rear, a sign of the agricultural origins of the community. The other, constructed in 1956, is one of the few structures that disturb the historical character of the green.

In 1901-1902 the Daughters of the American Revolution commemorated those who fought in the Civil War by placing an iron cannon pointing south on a granite base and a stack of cannon balls on the green. Next to it is the Connecticut Historical Commission marker. Other than the clipped yews near it, the flagpole next to the Old Town Hall, and the previously mentioned trees, no effort has been made to turn it into a landscaped park.

Although the larger Union Grove to the west of the green is privately owned, it is used for public celebrations. Mature white pine, oak, birch, maple and hemlock trees interrupted by rock out-croppings cover the Grove. A footpath from Town Hall Road and a rough track for vehicles from Kinney Hollow Road lead to a 20 by 40 feet wood frame picnic pavilion (c. 1984) and a stone barbecue pit. Also in the Grove near the intersection of Kinney Hollow and Town Hall Roads is a rough-hewn granite slab with a bronze commemorative plaque honoring the site of the first meetinghouse.

As well as serving a commemorative function, the green is used as a meeting place for parades and craft sales. An Old Home Day celebration is held at the pavilion on the third weekend of August when there is a barbecue and an evening dance.