For an extraordinary Gaudí experience, climb up above Plaça de la Bonanova to this private residence built between 1900 and 1909 over the ruins of the summer palace of the last of the sovereign count-kings of the Catalan-Aragonese realm, Martí I l'Humà (Martin I the Humane), whose reign ended in 1410. In homage to this medieval history, Gaudí endowed the house with a tower, gargoyles, and crenellated battlements; the rest—the catenary arches, the trencadís in the facade, the stained-glass windows—are pure art nouveau. Look for the red and gold Catalan senyera (banner) on the tower, topped by the four-armed Greek cross Gaudí often used. Over the front door is the inscription "Sens pecat fou concebuda" ("Without sin was she conceived"), referring to the Immaculate Conception of the Virgin Mary; on either side of the front door are benches with trencadís of playful fish bearing the crimson quatre barres (four bars) of the Catalan flag as well as the Corona d'Aragó (Crown of Aragón). Still a private home and long closed to visitors, the Torre Bellesguard is now accessible to small groups. Sign up (firstname.lastname@example.org) for a guided tour: this is a treat not to be missed.