The General Assembly of Connecticut (state legislature) met alternately in Hartford and New Haven since before the American Revolution.

After the Civil War, the complications of this plan began to be evident, and both Hartford and New Haven competed to be sole state capital.

Upjohn won, but Batterson, a stone importer and merchant and not an architect, was named the building contractor.

[4] The New York Times described the newly constructed building: "a vast mass of white marble (is) this imposing structure, and in the dazzling sunshine of a New-England Summer noon sparkles like a fairy palace of frost work.

"[5] The site of the Capitol was chosen since it is adjacent to Bushnell Park and had access to more surrounding open space than the older building in the immediate downtown.

Some galleries on the building's main floor hold historical artifacts, principally battle standards of Civil War units.

The statues are of politicians and other people important to the state's history, including the Reverend Thomas Hooker (1586–1647), Major John Mason (1600–1672), Governor John Winthrop Jr. (1605/1606–1676), Roger Sherman (1721–1793), Revolutionary War Governor Jonathan Trumbull (1710–1785), Noah Webster (1758–1843), General Joseph Hawley (1826–1905), Civil War Secretary of the Navy Gideon Welles (1802–1878), and United States Senator Orville Hitchcock Platt (1827–1905).

The typanum of the main east door holds The Charter Oak by Charles Salewski, the first piece of sculpture created for the Capitol.

The building's dome originally had a large statue on top, named The Genius of Connecticut, which was taken down in 1938 after being damaged in the great hurricane of that year.

The statue was cast in bronze from a plaster original, and was 17 ft 10 in (5.4 m) tall, and weighed 7,000 lb (3,175 kg).

5273 before the General Assembly sought authorization to make a new casting of the statue to restore the design for the capitol dome.