Norway's Trollstigen (Troll Footpath) winds down a hair-raising 9% gradient with 11 hairpin turns between Valldal and Åndalsnes. Legend has it that trolls wander the road at night, turning into towering rocks in the sunlight. Engineers the world over have to consider not just the terrain, but also local traditions when designing bridges and byways. Case in point: This Icelandic town recently re-homed a boulder -- home to elves, in folklore -- before construction began. Your civil engineers will conquer new territory with this month's activity. Happy trails!