Welcome to Firelink Shrine. Like, "this is your home now." You talk to the guy there, he tells you that there are two bells of awakening: one far above in the Undead Church, and another far, far below at the base of Blighttown.
To get to the first bell, you climb. You go up from Firelink through an aqueduct, you make your way through Undead Burg, moving noticeably upwards the whole time. At the end of the Undead Parish lies the bell, which means fighting your way through the courtyard and climbing to the top of the church.
The entire time, at least for me, you know exactly how far away you are from Firelink Shrine. The layouts of areas have been seared into your mind through countless deaths. After ringing the bell you know you're going to have to make it back on foot, but it's downhill from here.
In the courtyard you find the basement key, which leads to the lower part of the burg. Through the door it unlocks, you descend a spiral staircase in a giant bridge tower that loops around on itself at least four times. When you step out from the tower, fires, rabid dogs, and backstabbing undead thieves are there to greet you. After killing the boss that guards the entrance to the depths, likely after many tries, you're ready to descend even further.
The Depths are truly awful. They're sewers full of rotting slimes, rats, and basilisks, the last of which will cut your health in half if you die to their cursed breath attack. A single bonfire sits at the end of a long hallway in a cramped room- this practically becomes your new home, as climbing back out feels impossible. You're so far away from Firelink--and you're not even halfway to the bell yet.
After stumbling through the depths and killing the boss (more than likely while having only half your health bar), you'll obtain the key to Blighttown. A big, imposing gate sits in the main room of the Depths. Upon unlocking the gate and stepping into the entrance of a huge well, the lighting immediately changes from a dingy yellow to a toxic dark green. Oh no.
You make your way down the well, descending poorly made wooden ladders and platforms. You are at the top of blighttown. Mercifully, there is a bonfire fairly close to where you exit the well. Blighttown is exactly as pleasant as it sounds. It's filled to the brim with things that will poison you, and the enemies are less than pleasant. Even the terrain fights against you: you'll have to brave collapsing scaffolding and swaying log bridges to even have a chance of making it to the posion swamp that lays below.
If you're like me, you missed the bonfire tucked away in a sewer drain at the bottom of Blighttown, which means that you had to do the entire run through the derelict hellscape for every attempt at the boss. Quelaag resides within the giant web-covered tree, and she's very tough--especially considering all of the ailments that you possibly have at that point: curse, poison, degraded weapons/armor, and/or unupgraded gear/estus. The thing is, you're so goddamn deep that climbing out of hell seems utterly impossible, so you carry on no matter what.
After a victory against quelaag, you ring the second bell and continue on a path below its tower. Laid out in front of you is the Demon Ruins, a giant expanse of crag and magma. What's more is that it keeps going down. All the way through the ruins, to the Lost Izalith, and down to the Bed of Chaos.
Around this time you'll realize that you've done what you came here for, and you're going to have to climb back out. You know exactly how far away you are from Firelink Shrine.