The Roofs is the first map in the Red Sea Campaign by SilverRagout:
*The Metro, school, theater
*Finale on deck
Download the map from here:http://www.l4dmaps.com/details.php?file=342
Extract the files and copy them to: C:\Program Files\Steam\steamapps\common\left 4 dead\left4dead\maps
open the Console and type:
This looks like a promising start to the campaign with a versus map also available!