I loaded it up and it took ages - a lot of resources must needs be loaded. I flew around in Creative mode to get the lay of the land, but the chunks or whatever they're called loaded very slowly so everything was invisible at first.
I tried typing in /seed to get the seed, but no info about the seed was returned. Maybe I used the wrong command, or can a world have no seed number?
I don't know if it is worth spending any more time exploring this world. The main attraction seems to have some puzzles to get in, but I hate puzzles so would probably just break through the walls.