Warp build is always the default place for people to build in. There are no restrictions on where you can build here, except that you can't build or touch anyone else's build. Also, builds are supposed to be spaced apart, there should be at least 20 blocks of empty space (or road or landscaping) between buildings. Otherwise it gets too jumbled.
It is also recommened that you protect your land using Residence. Its the best way to stop grief.
There have been 7 /warp builds so far.