The future success of London depends on creating vibrant public spaces that are accessible to all, well-connected by transport and surrounded by excellent amenities. Where will these opportunities coexist in the coming century? River rooms are exemplary public spaces along the Thames. As London grows and densifies, it will increasingly depend on such places that are accessible to all, well-connected by transport and rich with amenities. David Kohn, architect of a Room for London, discusses his ideas for a new structure in Rainham.