As viewed from the water, the Copenhagen Opera House is quite an imposing structure. Clocking in at a cost of over half-a-billion (yep) dollars, it is to date one of the most expensive opera houses ever constructed. It actually resides on its very own island, Holmen, but due to its close proximity to the shore it doesn't really come across that way. The only link to land is via two enormous bridges made of aged oak. And the overall architecture of the building itself is only surpassed by the amazing voices that reside within its walls.