If you have been to Barcelona you probably heard of the arquitect and artist Antoni Gaudí, the constructor of La Sagrada Familia and several other modernistic buildings in the center of the city and elsewhere in Spain. You might have overlooked Park Güell though because it is located at some distance from the inner city. I am not going to try to tell you what you can expect by going there but instead suggest that you follow this link to a pretty good Wikipedia article.