CMS solution to manage multiple sites

Hi, need a CMS/Portal solution to manage multiple sites from a single set of code. The main purpose is get something easy to maintain. Any Open Source solution based in PHP are welcome. If is a propietary solution will need full source no code, no encrypted. Main requirements: -Allow maintain multiple sites from a single set of code -Design easy to implement and maintain in a separate layer -Multilingual websites -Manage articles and blogs with user comments -Robust captcha module -Forums -Directories with company/main item profile and products/subitems -Easy menu and page content maintenance -URL friendly -Different user profiles as flexible as possible. Most of the times admin and registered user would be ok, but I can figure cases will need admin, content managers, companies and users, for directories and this kind of sites. For this project you have to setupt software in our server and create two first sample sites. If you choose some Open Source solution will look for two templates for those sites if is a propietary one will create design and you'll have to integrate. You'll have to give a clean solution, without unneeded options in public or admin side. The whole setup and configuration process must be totally documented. If choose an Open Source solution must document also any change you do that could affect to maintenance or upgrades. Bid only if you know very well some OS solution or you have the right propietary one. Thanks Pepe