Portal 1 Level 4 Ported into Portal 2.
Lots of P in the title...
Anyway here is my port from level 4 of Portal 1 into Portal 2. (You put this in common/portal2/portal2/maps
The sign will not work I will make sure to update that later 
It is not the finished version, still lacking some other small details.
It's not a BIG challenge of playing .. honesty it's pretty easy. just something cool to check out.
It's a bit strange to put that file here; I'd upload your map as a release via the download section.
And if it's not finished yet; Add it to the WIP section 
Isn't someone else already re-making the entire first Portal?
There are various projects on the way:
Audiotrash is working on Portal: Deja-vu: http://www.moddb.com/mods/deja-vu
and another bunch of people are working on Portal: Alive & Kicking: http://www.moddb.com/mods/portal-alive-kicking