The Bridgelands are the long stretches of land before heaven's alter. There is a large chasm which, if one falls through, leads to Second Eden.  There is a rope bridge over the chasm that only the ones who want to reach heaven's alter with pure intentions may cross and survive.  Semiramis will often try to show travlers the way across the chasm that does not include crossing the rope bridge.  However, this will not lead to heaven's alter.