The Devil, king of evil, is one of the most interesting spiritual concept, for if one can't be sure of God's existence, the existence of evil and of entities who/which impersonate that are beyond doubt.
I always thought that the Edificio Telefónica is the place where the devil lives (New York as suggested in the movie The Devil's Advocate is also a good place but that would be too trivial and trendy, the Devil is subtle).
A sculpture from Jacob Epstein representing The Archangel Lucifer as a mixture of male and female attributes, in Birmingham's round gallery with the force of nature. The style of Epstein was particularly apt at depicting the devil (as well as Einstein).