Entry to Parc Guell is free (though the small museum costs to get into. You can also take a Parc Guell Guided Tour for the full story behind the park.
See also: Sagrada Familia (by the same designer as Parc Guell)
Antoni Gaudi's Parc Guell, Barcelona
Parc Guell, Gaudi's park in Barcelona.
Parc Guell, Barcelona
Image: Damian Corrigan