So this area is quite difficult, but if you got this far, or to this place, you will know why.
Nearby, there is a location called Swan Lake. Inside that lake is something I call a 'gatekeeper'. There is a Behemoth named 'Swan' who emerges from the lake when you are close. Make sure to keep your distance and have a Fat Man with I would say 4-5 Mini Nukes, just in case. But be on the lookout when fighting this guy because he throws rocks, and can kill you with 1, and if you are lucky, 2. After you kill him, there will be a few enemies but nothing too life threatening.

There is a subway, which is another sidequest, but I will leave that to you.

This is the start of the trail, REMEMBER THIS SIGN
There is a tour bot in the picture, so you will be fine when he amerges from his pod. You can talk to him and he will tell you a little about the trail, but not much.

7-A (trAil)
Now, pay careful attention to the red-brick path, it turns alot and it is mostly covered by debris so I will try as much as I can to help out.
On this marker, the A on "Trail" is bracketed, this will help at the end of the trail. At the bottom of all the screenshots and the descriptions, I will put the code in order.
The numbers mean where in the code this letter is need, there are eight of these total.

4-L (traiL)
If you follow the red-brick trail, it will lead to the foot of a building and you will discover it. At the base of the steps, will be the second letter on the Path. In this spot, the path is easy to follow but soon it will be difficult.

2-A (trAil)
So the first screenshot is of where the next marker will be. (I am currently standing on it).
This is where enemies will start to be. There will be 3-4 Feral Ghouls at this location. Behind me is a bus infront of the cemetery.

This is where it starts to get interesting. This is where you have to see where the path cuts off do a bit of guess and check, even though it is a straight path. The trail is blocked by all the dirt so just go down the alleyway. There might be enemies, 2-3 Mongrels. Up the street a little more after the hump, there will be a building with 3-4 Super Mutants and one is a Legendary.

6-O (freedOm)
This is where the next one is. I toke a picture of the loacation as well, and to go off of. But a trail should lead this way.

This is the location of the next marker, which is NE from the last marker. This is over a bus, but if you jump down, 2-3 Feral Ghouls will spawn. In the top left corner of the screenshot is a pack of Raiders but you really dont need to botherr with them, sneaking by will be fine.

3-I (traIl)
This is an i not an L so pointing that out now.

If you sneak around the left street after finding the next marker, there will bbe these stair which make the trail cut off, but trust me, go up the stairs, we are not even half way through yet, here comes the difficult part.

At this place, there will be 1-2 Mutant Dogs and 3-4 Super Mutants, 1 will a Missile Launcher. I think he has 3-4 Rockets until he runs out so wait that out and kill the charging Mutant Dogs.
PRO TIP: use 10mm pistols for this, they are very effective against anything, I would say laser Weapons, but they are a tad bit more expensive.

5-R (tRail)
This next marker is at the base of the blazing fire.

Now, follow the trail to the back of the building and keep going to the left. And when you are at this point, take the next right, past the fallen billboard.

At this point is where the next marker is if you didn't get lost. There are 2-3 Super Mutants and a Mutant Dog.

8-D (freeDom)
After this point, it should be a cake walk. Keep following the red trail and it will lead you to the last marker.

At the base of the stairs is the final marker: 1-R (fReedom)
The protaganist will say something to himself, and now you enter the church.

As you enter the church, there are a Feral Ghouls throughout. 7, 8 tops. Directly to the right of this screenshot, which is just outside of the entrance you just entered, is this:
That is where you want to go, after you defeat all the Ghouls on this level. There is a door to the right of this Icon the "Lantern" from earlier.

You will head down the stairs and into the catacombs which have 3-4 Feral Ghouls in it. After you do that there will be a turn to the left with 2 more Ghouls.

After taking down those 2 Ghouls, comes this. The dial to the right with the cords attached to it will open a door, with the code and order from before
1. R (fReedom) If this doesn't work right just use the 'R' in 'Trail' and do everything else the same
2. A (trAil)
3. i (TRAiL)
4. L (traiL)
5. R (tRail)
6. O (freedOm)
7. A (trAil)
8. D (freeDom)
If done correctly, there will be the sound of stone moving around and the wall will slide back. Like I said before, not spoiling what is inside, that is for you to find out.

This is my first ever real walkthrough on something and leave a message if this help and if you already completed this quest, let me know what I missed, and I will look into it!
~Keyboard Disconnected