Uhh you can't save your map/server state...?

[moo10032]

It seems as though you just simply can't save the state of your server...? Meaning like the placement of objects and items and NPC's and props etc. I have just finished playing with friends all night in Garry's Mod and now I want to save and close down the server to play again tomorrow night. After extensive googling I could not find a single bit of information on how to save my srcds's servers state? Seriously? How do you save!?