The website is currently being privately tested and is due to be unveiled in full later this summer. BA has only released limited information on the secretive project, alluding to an online community delivering recommendations of the best places to go in both cities. The airline said the project is at a very early stage.
The move marks one of the biggest forays into social media from a major brand to date. Dr Martens, Pedigree and Coca-Cola have already launched such social networking initiatives.
BA has launched a blog in tandem with Metrotwin.com and will announce updates on the project on social media service Twitter.