Churches are built as an act of faith and worship, but some builders also know the value of novelty. If you can get people to come and visit out of curiosity, they may stay for worship. That's not the only reason some churches end up being extreme, but it works to draw people in. Several churches built high on top of barely accessible rock pillars in different parts of the world make the statement that just getting there is an act of sacrifice. Some people think that way, while others just take it as a challenge. Some churches are unusual because of events in their history, like the cathedral in St. Petersburg that the Soviets spent a half century pretending its not a church- yet they couldn't bring themselves to tear it down. Great Big Story looks at seven of the most unusual churches in the world, any of which would make a great vacation destination or an adventurous pilgrimage for the faithful.