The name of the place... Babylon 5^H^H^H^H^HThe Ark....

The "ark" ship is almost exactly the same idea as the titular space station in the drama series Babylon 5, complete with a centrally located light source, and a miniature terraformed landscape. And in B5, the population was the same as this thing... 250,000 beings.

Except that National Geographic's pseudo-reality trumps fiction - B5 was five miles long and this thing is 15 miles long. The external CGI shots were terrific.

Humans and no aliens wrapped in seven million, five hundred thousand tons of spinning metal, all alone in the night.... (just multiplying B5's weight stats by 3.)

I actually rate this "documentary" as pretty good SF.