The church has a large main floor consisting of an atrium with some broken collectors and two partially collapsed balconies, both reachable by stairs at the back, or a collapsed part near the front door to the right. It also has a fairly long basement tunnel—the 18/19th century crypt beneath the church—reachable to the right of the main door.
The basement tunnel has a golden Freedom Trail seal on the wall. The phrase "The Freedom Trail - Boston" is on a turnable wheel with an arrow on the center. The arrow points to a letter and one can activate letters in a certain order to gain entrance to the Railroad (by spelling 'railroad' on the wheel) as part of the quest Road to Freedom. This will gain access to the Railroad HQ.
At the far wall of the atrium, opposite the passage leading down to the crypt, there is a small staircase with a door to the Old North Church steeple. The steeple is actually part of the exterior environment but is fully enclosed except from above; the door exits into the bottom of the steeple stairwell which can be used to reach the roof of the church.
There is a Combination-Riddle in the tunnels. The password is to spell "railroad" with the wheel (it does not matter which way the wheel is turned).
While there are multiple letters in some cases (such as "R"), note that only one will be able to be "selected" by the spinning wheel. This means one must enter the same "R" (in the same location on the wheel) twice, for example.
pc In some cases, the game will freeze when attempting to enter certain buildings in Boston Common, including Old North Church, making the quest Road to Freedom impossible to complete. The console command coc OldNorthChurch01 will teleport the player character into Old North Church, past the entrance to The Railroad. The console command tcl must be used to go through and open the door to The Railroad properly. Exiting through the front entrance works afterwards.表达式错误：未预料的<操作符
pc Sometimes the Old North Church's front door at the end of the trail can't be accessed making it impossible to proceed. Saving/quicksaving and reloading, even directly in front of the church entrance, should restore the door to functionality. Otherwise, reload a previous save game before entering the Old North Church's general area or use the console command listed above to teleport directly inside.表达式错误：未预料的<操作符
↑Fallout 4 Vault Dweller's Survival Guide - Page 467: Using a plan devised by Paul Revere, Robert Newman climbed to the top of this church and lit two lanterns to alert patriots that the Redcoats were coming up the Charles River. This inspired Longfellow’s famous verse “One if by land, two if by sea.”