Discover the London skyline that might have been, and the story of Venice’s Ca’ d’oro

The skylines of London and Moscow might have been very different. Two exhibitions in London look at what could have been. At the Royal Institute of British Architects, ‘Mies van der Rohe & James Stirling: Circling the Square’ examines two proposals for the same site in the City: van der Rohe’s unrealised Mansion House Square skyscraper (above) and Stirling’s No. 1 Poultry (8 March–25 June; architecture.com). Meanwhile, at the Design Museum, ‘Imagine Moscow: Architecture, Propaganda, Revolution’ showcases plans, posters and magazines dating from the 1920s and 30s that imagine an idealised capital which was never realised (right, 15 March–june; designmuseum.org).