The Sim City 2000 instruction book mentions a little tidbit regarding the Launch Arcologies. They tell you that if you build enough of these, you could see the final secret to SC2K, which I'm assuming is the actually launching of the Arco into space. So my question is, how many of these things do you have to build because I'm running out of room in my city!!!

How do you build Arcos? I always wanted to build one but I was never allowed to

Launch Arcos become available as well as all the other Arcos when you get your population up to a certain number. I believe it's one million citizens to start building them, but don't quote me on that. Just start building up your population and eventually it'll show up on your list.

I know this is an old topic, I just thought I'd answer. You need around 400 Launch Arcos. If you run out of room to build in your city, just destroy a 4x4 block of residential homes and build one there.

I've had 417 in my city for over 700 years and they still haven't launched .

Hmmm, either I don't have 400 arcos yet, or I totally missed out on the launch while I was sleeping.
I tend to make sure I'm making a profit, then I'll leave my Playstation on while I go to bed so that when I wake up, I'll have a ton of money to spend.