I don't know why I like all these houses with crazy lines, but I always seem to ;-).

This house belonged to the secretary of Eusebi Güell, the industrialist and Gaudí patron who established this industrial estate to house his workers. The bat (barely visible over the top window) was part of the Güell coat of arms. Apparently there is always a pigeon sitting atop the bat, looking over its shoulder. (Thanks to Jose for the tip on the information!)