Megadungeon Hall of Fame: "The Dungeon as a Mythic Underworld"
The Dungeon as a Mythic Underworld is a classic megadungeon blog post. You can find plenty of comments and references to it, which speaks to its influential place among many gamers. Alas, the post itself is no longer available, with the demise of the blog Philotomy's Musings. However, the content is still available online with only the slightest bit of work. Pages 22-24 of Philotomy's Dungeons & Dragons Musings (free PDF) preserves the content of the original blog post, The Dungeon as a Mythic Underworld. Be sure to follow the link and check it out.