The same travertine quarries near Rome that built St. Peter's Basilica and the Colosseum are still being dug out today, providing the distinctive pock-marked rock to build a new generation of churches, temples and mosques worldwide.
Experts say a weekslong "snow drought" in Norther California's Sierra Nevada helped set the stage for Tuesday's deadly avalanche, after several feet of new snow fell on an earlier layer that had hardened.