Control.
It's the one level where you can die before even getting out the elevator you start in... On 00 Agent (and possibly Secret I can't remember) there is a Drone Gun PERFECTLY positioned to ruin you, opening fire before you even step through the doors. Like the other two Drone Guns in the opening area it's got unlimited range and is hard to see in the darkness. The rest of the complex's Drone Guns are slightly more visible but make up for it with numbers and guard support (there's one corridor with 4 or 5 of them). After about ten deaths, a good player will be able to make it to the control room and watch Natalya be gunned down/blown up for the umpteenbillionth time.
Honorable mention to Aztec.