Solo, Parc del Laberint d'Horta works.
A serene 18th-century estate garden of clipped-cypress terraces, fountains and statues, with a genuine cypress hedge maze at its heart — and daily visitor caps that keep it dreamy and near-empty. But be honest about the trade: it's a real haul out to Horta (metro to Mundet, then an uphill walk), the maze is small and quickly solved once you're in it, and there's little else nearby. The clean fit verdict: make the trek if you specifically want a quiet, romantic, photogenic garden away from every tour group; skip it outright if you're tight on days or want a maze that'll actually challenge you — central Ciutadella gives you green space for zero effort.