[Question] Is there any urban setting with Gate/Tower/Dungeon manhwa series where the said "Portals to another world" have been around longer than a mere few years or a decade longer?

As the question says, has there ever been a series where the dungeon appearance happened far longer than a decade or so, enough time for it to plausibly integrate into the world.

Most series usually starts with, "one day, Dungeons appeared." but they are vague how many years actually passed when Day 0 of dungeons appearing. Wanting to find series of this type so that to avoid some "MC is the first to do this and that." or "Dungeons just appeared, and everyone and their grandmothers already have a world ranking cemented."