“It has always been a world of its own,” writes David Kynaston, a historian, in the introduction to photographer Polly Braden’s new book London’s Square Mile: A Secret City. But although it is a world familiar to those who live and work there, Braden’s photographs depict a landscape of concrete and steel where humans seem superfluous — as though the Square Mile was a giant machine that runs itself.

The photos, taken over 12 years, show that the City is more than just banks and bankers, capturing everything from aged stone pillars to Occupy-era street protests. But the real treat is seeing familiar territory, and the people in it, framed by Braden’s probing, thoughtful gaze.