I'll be traveling with my dad who is 79 and in decent shape, but with arthritis in his hip. I'd like to take a taxi to the "top" of Parc Guell and walk down so it is easier on him. Can someone tell me where we should have the taxi let us off so that we are walking mostly downhill but still seeing the important sites within the park? I cannot find a good map of the park's interior with sites noted anywhere. Thanks!