Bridges are among the most favored of all human structures. They serve us well, make a bold visual statement, and open the door to a storehouse of memories. Who doesn’t admire the elegant lines of a suspension bridge? Who can look at a covered bridge without thinking of a time when life was simpler and slower and friendlier? This week's quiz will find out how much you know about the bridges and bridge-related things in our national parks. Answers are at the end. No peeking.