Waltham is a city in Middlesex County, Massachusetts, United States, and was an early center for the labor movement as well as a major contributor to the American Industrial Revolution. The original home of the Boston Manufacturing Company, the city was a prototype for 19th century industrial city planning, spawning what became known as the Waltham-Lowell system of labor and production. The city is now a center for research and higher education, home to Brandeis University and Bentley University as well as industrial powerhouse Raytheon Technologies. The population was 65,218 at the census in 2020.Waltham has been called "watch city" because of its association with the watch industry. Waltham Watch Company opened its factory in Waltham in 1854 and was the first company to make watches on an assembly line. It won the gold medal in 1876 at the Philadelphia Centennial Exposition. The company produced over 35 million watches, clocks and instruments before it closed in 1957.

Cambridge ( KAYM-brij) is a city in Middlesex County, Massachusetts, and part of the Boston metropolitan area as a major suburb of Boston. As of the 2020 United States Census, the city's population was 118,403, making it the fourth most populous city in the state, behind Boston, Worcester, and Springfield. It is one of two de jure county seats of Middlesex County, although the county's government was abolished in 1997. Situated directly north of Boston, across the Charles River, it was named in honor of the University of Cambridge in England, once also an important center of the Puritan theology embraced by the town's founders.: 18 Harvard University, the Massachusetts Institute of Technology (MIT), Lesley University, and Hult International Business School are in Cambridge, as was Radcliffe College before it merged with Harvard. Kendall Square in Cambridge has been called "the most innovative square mile on the planet" owing to the high concentration of successful startups that have emerged in the vicinity of the square since 2010.

Massachusetts, officially the Commonwealth of Massachusetts, is the most populous state in the New England region of the United States. It borders on the Atlantic Ocean to the east, Connecticut to the southwest and Rhode Island to the southeast, New Hampshire to the northeast, Vermont to the northwest, and New York to the west.

Boston (US: , UK: ), officially the City of Boston, is the capital and most populous city of the Commonwealth of Massachusetts in the United States and 24th-most populous city in the country. The city proper covers 48.4 square miles (125 km2) with a population of 675,647 in 2020, also making it the most populous city in New England. It is the seat of Suffolk County (although the county government was disbanded on July 1, 1999). The city is the economic and cultural anchor of a substantially larger metropolitan area known as Greater Boston, a metropolitan statistical area (MSA) home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest MSA in the country. A broader combined statistical area (CSA), generally corresponding to the commuting area and including Providence, Rhode Island, is home to some 8.2 million people, making it the sixth most populous in the United States.Boston is one of the oldest municipalities in the United States, founded on the Shawmut Peninsula in 1630 by Puritan settlers from the English town of the same name. It was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill and the siege of Boston. Upon American independence from Great Britain, the city continued to be an important port and manufacturing hub as well as a center for education and culture. The city has expanded beyond the original peninsula through land reclamation and municipal annexation. Its rich history attracts many tourists, with Faneuil Hall alone drawing more than 20 million visitors per year. Boston's many firsts include the United States' first public park (Boston Common, 1634), first public or state school (Boston Latin School, 1635) and first subway system (Tremont Street subway, 1897).Today, Boston is a thriving center of scientific research. The Boston area's many colleges and universities make it a world leader in higher education, including law, medicine, engineering and business, and the city is considered to be a global pioneer in innovation and entrepreneurship, with nearly 5,000 startups. Boston's economic base also includes finance, professional and business services, biotechnology, information technology and government activities. Households in the city claim the highest average rate of philanthropy in the United States; businesses and institutions rank among the top in the country for environmental sustainability and investment. The city has one of the highest costs of living in the United States as it has undergone gentrification, though it remains high on world livability rankings.