The project is being built and directed by Arceusrules98 on the server Edogg, and was hinted to in his first episode, where he found the large mountains in Minerva Mountains. He saw those beautiful four pillaring mountains that seemed to connect, and knew that were the place to build his grand project. What the project is is a secret, of course, and it is forbidden to come close to it while filming. However, right now it's okay, since items are only collected in a storage for later building. The storage will be erased after building is done as well.
Floralpikmin99 found the storage and showed it in an episode while she was playing with Austin and luckily, nothing had been built. But since that time, the location is no longer a mystery. The building that was going to be there will probably never be built, as the server will be restarted with the 1.7 update, but the project will be re-imagined for said server.
It won't be built on the current server. But when the server is restarted, it will be built there instead.