1. On May 27, 1637, the first battle of the Pequot War took place in present-day Mystic, Connecticut, involving English and Mohegan allies against the Pequot tribe. The conflict would last until July 1638, resulting in the virtual extermination of the Pequots and opening up more land for English colonization.

2. The Massachusetts State House, located on Beacon Hill in Boston, was completed on May 27, 1798. It has served as the state's capitol and home to the government for over two centuries, and is renowned for its striking architecture, including the iconic golden dome.

3. On May 27, 1861, the Civil War was officially declared by Massachusetts Governor John A. Andrew, making Massachusetts one of the first states to answer President Abraham Lincoln's call for volunteers to put down the rebellion in the South.

4. The Boston University Bridge, which spans the Charles River connecting Boston and Cambridge, was opened to the public on May 27, 1928. The bridge was designed by architect William G. Hunt, Jr., and has since become an important landmark and transportation hub in the metropolitan area.

5. May 27, 2002 marked the start of the historic Big Dig project in Boston, one of the largest and most expensive public works projects in United States history. The project involved relocating a major highway and building a network of tunnels and bridges beneath the city to improve traffic flow and urban development. It was completed after several setbacks and controversies, and has had a profound impact on the city's infrastructure and economy.