Small church themed start map. Has nice decorations, but is a bit tight. Contains portal selections for all difficulty levels.
graveset.bsp - Link to Nightmare 100% walkthrough: https://youtu.be/438OI9QRDaI
Catacombs and cave systems. It feels pretty satisfying blowing up zombie after zombie. The map is interesting and looks decent in most spots. Some rooms do look like they are decorated with somewhat random geometry though. Everything is pretty tight, making movement difficult in a lot of places. It kind of diminishes the satisfaction of killing enemies, making the map feel average.
The way to the Gold Key is also pretty obscure.
undrgrvs.bsp - Link to Nightmare 100% walkthrough: https://youtu.be/UWmuTKgmamQ
Overall, not a terrible map. Just average.