All the World's a... Dungeon?

Disclaimer: This may be (and probably is) old news to many. Humour me and read it anyway?

I have been pondering the nature of dungeons recently. I love them. They can be an absolute blast to play in and to run, and the presence of their name in the name Dungeons & Dragons is no paltry attribution to alliteration.
Lately I have been thinking there are several elements that make a dungeon (especially the more old school type, less the modern "naturalistic" and "real" (hah) style of dungeons) so enjoyable, mysterious, and such great locations for adventure.
I think most people agree that "dungeon" in game terms can be a dungeon, a mine, ruins, a castle, etc. What I'd like to do is expand that working definition to include the entire world.

To quote Inigo Montoya, "Let me 'splain. No, there is too much. Let me sum up..."
Dungeon Key Elements:

• Sense of dread/fear/wonder
• The dungeon is out to get you
• Traps, doors not opening automatically, wandering monsters
• Exploration and mapping
• Hidden rewards / treasure
• Big bad pulling the strings

I do not see how any of those elements are NOT present in the above-ground. Obviously, there's a tradition within D&D and other RPGs of hexcrawl-adventure and such, which is much the same, but who's to say an urban adventure is not a dungeon crawl? The timing may be a bit different--it has a different beat or rhythm--but streets are corridors, buildings are rooms, and there are still treasures to be found and big bads to topple. (In fact, a city might be considered the equivalent of a megadungeon, as buildings, castles, sewers, dungeons can all be part of the city.)

Again, this is probably old news to you, but it was a sort of eureka moment for me recently and has made laying out adventures for my upcoming game way easier.

We now return you to your regularly scheduled internet.