Although technically not part of Bushnell Park, the magnificent state Capitol building cannot be ignored since one of the reasons Bushnell Park was created was to provide a proper setting for this imposing building. In 1873, the citizens of Connecticut voted to name Hartford as the single capital of Connecticut. Before then, Connecticut had two capitals, with the state legislature alternating between New Haven and Hartford.

Originally, the west side of Bushnell Park was going to be the site for the building. However, an impassioned last-minute protest by Dr. Bushnell himself and a suggestion from the editor of The Hartford Times newspaper, Alfred E. Burr, resulted in the selection of the present site.

The architect was Richard M. Upjohn of New York, whose father, 30 years earlier, designed the famous Trinity Church on Wall Street in New York City. The building, opened in 1878, cost $3 million–way over the original budget of $900,000–caused when the first dome collapsed during construction.