1. On December 15, 1795, the first bridge in Connecticut was completed over the Housatonic River in Derby. The bridge served as a major transportation link between eastern and western Connecticut.

2. On December 15, 1814, the Hartford Convention began in Connecticut. The convention was a meeting of Federalist Party delegates from several New England states who opposed the War of 1812 and discussed possible secession from the United States.

3. December 15, 1832, marked the opening of the first public library in Connecticut, located in New Haven. The library was founded by a group of Yale College students who wanted to create a free lending library for the local community.

4. On December 15, 1888, the Connecticut State Capitol building was completed in Hartford. The building, which features a distinctive gold dome, houses the offices of the governor and the state legislature.

5. December 15, 1943, saw the start of the Hartford Circus Fire, one of the deadliest fires in U.S. history. The fire occurred during a performance of the Ringling Bros. and Barnum & Bailey Circus, and resulted in the deaths of 168 people, most of them children.