Tomb Raider 1 – Caves
The entire first level of Tomb Raider 1 (the original one, not the reboot) called "Caves" remade for the Source engine in its low-definition glory.
The scaling is (mostly) intact and all music and secrets are there. All item pickups are there as well.
Feel free to do what you want on this map, although I could mostly see people just building on it.
Anyway enjoy!