The crawling babies on the Zizkov Television Tower weren't there originally. "The tower was built without the sculptures in Prague between 1985 and 1992. Even without the alien babies it’d be strange looking. David Cerny’s sculptures was added in 2000 as a temporary installation but the public loved them so much that they were kept for good."
Also they have no faces. I love them too.
Virtual Tourist's first list is here, but finding decent pics is difficult. But wiki has an article on eyesores that's useful.