Princeton Architectural Press has just issued a paperback edition of Sidewalk Critic (£12.95) - a selection from Lewis Mumford's 1930s columns inThe New Yorker . 'Mumford's eye was as good as his conscience. He remains the unsurpassed model for an engaged architectural criticism, ' says Michael Sorkin in his back-cover blurb - and he is right. Some of the buildings Mumford mentions have disappeared, but his analyses are timeless. Whether looking at a health centre or a housing block, a skyscraper or a shoe shop, Mumford never lost sight of the city. It should be on your bookshelf.