"One if by land, two if by sea." If this phrase sounds familiar, it's because Paul Revere proclaimed them on his famous Midnight Ride, of which the Old North Church was his first stop. It was chosen as the site to send the signal that the British were advancing toward Lexington and Concord by sea, hence the two lanterns being raised as a warning. At the time, in 1775, the church's steeple was the highest in the city, and an obvious beacon to send messages from. This wasn't the first time Revere spent time in this church, he was also a bell ringer at the Old North as a child years prior.
The church was built back in 1723 and is the oldest church in Boston.