In the latter half of the nineteenth century, Boston transformed itself from a town on a tiny peninsula to a sprawling city. In part, this was done by creating new land in the Back Bay and South Boston, but the city gained a great amount of area by annexing its neighbors. The first was Roxbury, which joined the city of Boston 150 years ago this week. Dorchester, Brighton, West Roxbury, and Charlestown would follow. Other towns, like Cambridge and Brookline would not. Find out why in this weeks show.