In the case of Potosi, Venezuela, the government decided to evacuate the town and flood it. It made for a lot of heartbreak, and also some unusual sights.
In the case of Potosi, the story gets very interesting. In 1985, they decided to build a hydroelectric dam and flooded the town. But, in 2010 during a time of drought, the town came back again....
Above - before the flooding and after the water dried out.
Below - amazingly gorgeous drone footage of an uncovered church.