The Molecular Level

The Molecular Level is a quest and achievement/trophy in Fallout 4.

Quick walkthrough
Fist you must go to Boston Common, the trail stars next to the robot (Look on the ground). Along the trail and at the beginning you will find plaques on the ground that when interacted with your character will say a number and letter. The trail ends at the Old North Church the numbers and letters in order are as follows. 7A 4L 2A 6O 3I 5R 8D 1R.

After entering the Old North Church enter the main room and turn right, you will see a lantern painted on the wall in white. Underneath the lantern is a passage leading you to a paque on the wall with wires coming from it. the outer ring can be moved. The code to open this door is as follows. R A I L R O A D. After imputing this the door will open and you will be confronted by the leader of the Railroad Desdemona, you will then take the chip to be analysed, after finishing the analysis return to Virgil.