Son Doong Cave
It is the world's biggest (but not longest) cave and wasn't discovered until 2009. A 40-story building could fit into its tallest room. There are controversial plans to construct a cable car system through the cave.
It is the world's biggest (but not longest) cave and wasn't discovered until 2009. A 40-story building could fit into its tallest room. There are controversial plans to construct a cable car system through the cave.
