Robert Tannen is a hard guy to get a read on, at least in terms of most people's expectations. A sculptor, architect and urban transportation planner, he purposely takes an oblique route to and through these things. High-profile, connected with developers and politicians, he turns up all over the place, but in roles subject to speculation. Well established, however, are his roles with two city landmarks—the Contemporary Arts Center, which he co-founded, and the massive Greater Mississippi Ri...