The massive bridge spanning between Lothric and the Undead Settlement was built to connect the two. The Stray Demon patrolling the end closest to Lothric is the city’s gatekeeper, indicating that the gate he keeps is the structure behind him — one of several checkpoints along the bridge’s entire length, the gateway now blocked by rubble instead of a gate proper. The Small Lothric Banner likewise confirms that the path from the city to the settlement was also broken by the emergence of the High Wall, which only the bridge facilitates. Even the cloth map provided with the Collector’s Edition of the game orients the bridge toward the main gate to the city walls. There was undoubtedly a conscious decision to make the viaduct the main route to Lothric prior to our journey.
Some have argued otherwise, pointing to how the causeway clearly heads someplace to Lothric’s left rather than the gates to the city walls. Indeed, while a dead end in the final game, the bridge was intended to lead somewhere earlier in development. The map provided with the game’s official soundtrack CD in Japan labels it as a separate area called “Great Pilgrim Bridge” (巡礼の大橋) in obvious reference to the pilgrims of Londor littering the place. The Stray Demon also has the mechanical complexity to be the area boss. Cutscene triggers similarly confirm an unused transition from Lothric to the bridge, separate from the one dropping us off at the Undead Settlement — in other words, the Stray Demon’s end only accessible from Farron Keep in-game. And based on the numbering of these triggers, we would have gone there after heading to the town, defeating the “Lone King” of the “Ruined Capital”, (廃都) and then returning to defeat the Twin Princes in Lothric Castle. This sequencing indicates that we would explore the bridge as its own area roughly halfway through the story.
Considering how small this “area” is in the final game, it isn’t a surprise that it was downscaled to a mere extension of another area. Still, it evidently led to someplace important to the main plot at one point, which fits with cut content. Shinbo (神墓) is the internal name for a graveyard area which now only exists in the game files, though the assets for many of its headstones were ultimately reused for DLC. Since this codename describes graves of gods, I will refer to the area as “Divine Graves”. The map itself is untextured, but we can confirm from remaining assets that it would have been covered in trees and situated roughly just left of Lothric and behind the Undead Settlement. This matches the geography for the bridge’s “destination” in the Collector’s Edition map. Was the viaduct originally imagined as a path to the Divine Graves? If so, who are these gods, and why bury them in the kingdom’s nearby forest?
In all likelihood, it was to be the graveyard for the Lords of Cinder. The souls of all past Lords comprising a singular entity are considered gods. Likewise, the opening cinematic portrays the Lords’ burial ground with no distinct landmarks identifiable with the Cemetery of Ash, which the name would imply is exclusive to unkindled. We can thereby only infer that these entombed Kings of Kindling are somewhere within range of Firelink Shrine’s bell toll; given that Greirat apparently heard the bell from his cell at Lothric’s front wall, that is a wide radius. How convenient then that there would have been another graveyard for “gods” located directly in front of the Cemetery of Ash — we can even see Firelink Shrine in the background behind Divine Graves’ location on the maps. These two areas might have been intended to be part of one larger graveyard, perhaps with a shortcut connecting them, but the juxtaposition suggests a connection, regardless.
… Ah, you don’t seem to be a prison guard. More likely an outsider, and moreover, it’s after the sound of that bell… By any chance, are you a fireless ash?
Some have instead posited a connection between Divine Graves and the pygmies. The headstones with a hole in their center were ultimately repurposed for the pygmy capital, and the unused variants in particular have roots associated with human dendrification growing around those holes. There are also pots with similar holes and branches growing out of them. From this, it is theorized that Lothric would have been built upon an old pygmy burial ground, with the ancient men as its gods. However, even assuming that Lothric’s dramatic transition from Dark worship to firelinking is feasible, the hole imagery doesn’t preclude a Lord of Cinder’s grave — the ritual is mainly performed by bearers of the Darksign, after all. Inheriting the First Flame also doesn’t prevent the Dark’s stagnation, as Aldrich exemplifies. And finally, the area layout better comports with a Lords’ graveyard.
Examining Divine Graves’ low-resolution model, the area starts as the forest cemetery only to gradually become a series of ruins and caverns cutting deep into the mountain which Lothric sits upon. What could possibly be down there that would merit a cemetery just outside of it? The means to reach the First Flame. Indeed, the in-game process for reaching the Kiln is, admittedly, inefficient even for an emergency system. Surely, Lothric would have created a more straightforward passage to the fire hiding in this land akin to the Firelink Chamber in Dark Souls or Throne of Want in Dark Souls II, both of which were located basically beneath the castle lording over their game’s respective setting. This passage would also have to be located somewhere convenient for the burial of Lords and unkindled alike, much like Firelink Shrine. These caverns at Divine Graves check all the boxes.
Further supporting this is the presence of Consumed King Oceiros in this area. Though the boss was still only called “Dragon Angel” at this point in development, his model, animations, and dialogue are identical to his finalized portrayal. In other words, the character seems to have always been the mad king of Lothric who became a dragon and fathered Ocelotte out of a twisted obsession with siring a Lord of Cinder. In that case, his appearance in Divine Graves is no surprise. Much like how Oceiros went to the temple ruins leading to Firelink Shrine, the Dragon Angel would have gone to the Lord graveyard providing him similar passage to the Kiln of the First Flame. Based on his dialogue, he would have either been squatting there waiting on Ocelotte like in the final game or be somehow prevented from continuing onward, which would also explain why we are required to take an alternate path in our journey.
A graveyard for firelinking gods connected to the Cemetery of Ash, Firelink Shrine, and the Kiln of the First Flame would motivate the construction of a massive bridge with multiple checkpoints regulating traffic. The bridge’s direct connection to all the firelinking facilities would likewise prompt Lothric to send all its Undead to a settlement at the start of the causeway — definitely more reasonable than dumping all but a select few right at the city’s only entryway. Everything in the environment fits better with the bridge connecting to Divine Graves. The only issue is that the area was cut early in development, its assets ultimately repurposed for various others. Why then did the bridge remain orientated away from Lothric up through the game’s launch? Was there some sort of mix-up? That would explain why two different versions of the same map art were released in official products, at least.

Perhaps the plan initially was to keep Divine Graves in the setting as a location referenced but never visited, hence the bridge’s orientation. Then, as development progressed, the viaduct was reimagined as the path to Lothric, resulting in the art for the Collector’s Edition map. But the developers lacked the time or resources to reflect this change in concept in-game. The bridge’s location relative to everything else is visible from most areas above ground. And considering how easy it is to find incomplete geometry and textures for the surrounding scenery by simply looking below our immediate line of sight as is, FromSoftware was unlikely to reorient a whole set piece for every area. Item descriptions cover the intended idea, and the High Wall makes it easy to justify the radical shift in the ruined bridge’s positioning and height relative to the city gates. In the end, that is enough.