Manage the expectation first: this is not a lush garden, it's monumental hardscape — gravel avenues, clipped hedges, statuary and stone, with very little shade. People arrive picturing roses and leave footsore in the sun. Take it for what it is — an open-air sculpture park and a stretch of green air above a dense city — and the Buontalenti grotto, the amphitheatre and the rooftop views over the palace pay off. Go in spring or first thing in summer; midday in August is a punishing trudge up shadeless terraces.