Some sort of concrete bunker or dam place. With guns.
Doubletrouble was a long standing DA map that we played heavily during beta. It was cut from the steam release because it's too cramped and doesn't scale well with server population.
Regardless, I love it. So here it is.
As you can see, it's a bunch of blocky samey BSP right now. I tried to fluff it up a bit back in the day with props and decals, but gave up when we decided to cut it. If you want to edit the map, the .vmf is available for download [here](http://sync.doubleactiongame.com/Maps/stormy/da_doubletrouble.vmf "da_doubletrouble vmf download")
I haven't touched this map for a while so I can't remember much about its state in Hammer. I packed the BSP though so everything should be in there.
If you get missing stuff make sure you are using the Hammer that comes preconfigured with DA.