Berlin wall, Pillars of Hercules, arch dam, backstop, bank, bar, barrage, barrier, barrier of secrecy, bear-trap dam, beaver dam, blackout, boom, border, border ground, borderland, breakwater, breastwork, brick wall, buffer, bulkhead, bulwark, censorship, cofferdam, curtain, dam, defense, dike, ditch, earthwork, embankment, fence, frontier, frontier post, gate, gravity dam, groin, hush-up, hydraulic-fill dam, iron curtain, ironbound security, jam, jetty, leaping weir, levee, logjam, march, marches, marchland, milldam, moat, mole, mound, oath of secrecy, official secrecy, outpost, outskirts, pall, parapet, portcullis, rampart, repression, roadblock, rock-fill dam, seal of secrecy, seawall, security, shutter dam, smothering, stifling, stone wall, suppression, three-mile limit, twelve-mile limit, veil, veil of secrecy, wall, weir, wicket dam, work, wraps

For further exploring for "bamboo curtain" in Webster Dictionary Online