this place is what you would expect to find if you crossed alice in wonderland with les tuileries. it's the only park i've ever been to where the fantastic flora are outshined by the impossible combination of antigravitational architectural flourishes and the cacophonous colors of magnificent mosaic tilework abounding on benches and fountains and walls and ceilings.
to get there, you must take the metro train to lesseps and climb a fantastic run of steps (escalators are provided for the energy preservationist), but the ascent is well worth the expenditure. you can also opt to go an extra stop on the train to vallcarca and enter from a different entry point. either way, plan to spend at least half a day there taking in all of the many different sections of the park. it's invigorating!