From PathfinderWiki

Grenalthrost, or the Great Bridge of Grenalf, is a massive cyclopean bridge that spans a great crevasse in Iobiaria's Syrzemyan Highlands, allowing access to the Grenalf Plateau and the city of Kirya. The Great Bridge is one of the most treacherous portions of the Koloran roads, as many of its nefarious mechanical traps are still active, continuing to claim lives thousands of years after the fall of the Koloran Empire.1


  1. Steven Schend. (2010). Iobaria Gazetteer. The Varnhold Vanishing, p. 59. Paizo Publishing, LLC. ISBN 978-1-60125-234-0