Pat, another Calgarian, and the blogger behind Ode To Black Dougal, also has a little site called Red Box Calgary. The purpose of that site is to promote B/X Dungeons & Dragons games in Calgary, an objective I heartily endorse. He has proposed that we start up a new B/X campaign this Fall.
One suggested setting for that upcoming B/X campaign are the dank and horror-filled catacombs, crypts and tunnels beneath an ancient, sprawling and corrupt city. This setting possesses a certain appeal to me, as I am currently reading several of Jack Vance's The Dying Earth novels, and that setting reminds me of Kaiin, a crumbling city, whose abandoned outskirts and underground tunnels hold mysteries and danger. The idea behind the campaign is that the DM duties will rotate amongst the participants. If the other participants were up for it, that would allow each of them to develop their own portions of a shared world, and link them all together in a more-or-less coherent framework.
Another option is to create a Caves Of Chaos styled campaign, where each DM takes one of the cave entrances in a box canyon or valley, and develops it, allowing for later linkages between the complexes. The above art is inspiration for the later suggestion. The art is by Michael Komark, and is from the D&D 3.5 Players Handbook II.