Romeo and Juliet were upstairs asleep in the castle, and Franco Zeffirelli kept the night watch alone. He sat cross-legged on the old stone wall of the Palazzo Borghese and sipped brandy from a paper cup. Behind him, the wall fell 100 feet into the valley. Above him, the little town clung to the hillside, each house stacked above the last. And on the other side of the castle wall was the secret garden where the families of the Borghese had doubtless spent their afternoons 400 years ago.