One of the most amazing things about plants is their ability to grow through all kinds of obstacles. When trees manage to do so, the spectacle is even more amazing because it is on such a grand scale. There are even more cool ones when you follow the link.
Link
http://www.darkroastedblend.com/2009/09/living-growing-architecture.html
when someone wrote in the newspaper about their admiration of a small tree growing in a Wash DC subway station the authorities immediately sent someone out to cut it down.