The 907 - One has to be a member to view anything on this site, and I didn't feel like signing up. But maybe you do.
Action Squad - Inspiring site of a group of Minneapolis-based urban adventurers, featuring abandoned buildings and tunnels galore.
Buggrit Online - An unabashedly text-only urban exploration site is a rare find, but the interesting observations here come through pretty clearly without any pictures.
Exploring the Twin Cities - Urban exploration under Minneapolis and St. Paul.
Frozen Crystal Underground - A few stories and mission reports related to the discovery of the realms below the Twin Cities.
Midnight Group - Profiles of "bridges, rooftops, drains, sewers, power plants, abandoned buildings, caves, and many places one can only place in the 'other' category."
Minneapolis Drain Archive - Illustrated expedition logs from a small group of Minneapolis drainers.
Obscure Minnesota - An enthusiastic explorers accounts of his journeys to a wide variety of Minnesotan locales.
Project Neverwhere - So far, this is just a couple of pictures and a bookmark for a future site.
Strategic Beer Command - Oh those wacky Minnesotans.
Tunnel City USA - Float down the river and find out how and why the manmade and natural tunnels under the Twin Cities constitute one of the largest systems in the world.
Urban Speleology - Urban caving both man-made and natural caves in the area around the Twin Cities.