The Barco Borghese is an artificial esplanade built on about 180 underground rooms with concrete vaults dating back to the Roman period, to the first century BC. Perhaps these were the foundations of a villa. Among the facilities we can recognize tanks and warehouses, but it is not yet clear the significance of this esplanade. In 1567, the Altemps transformed this place into a place of hunting and realized the 'barco', i.e. a "fence for wildlife hunting." Subsequently, the Borghese turned it into an Italian garden integrated into the Villa Mondragone.