No one really knows what Castellum Aquarum is. It’s 8 metres tall, for starters, 36 metres long and 16 metres wide. Inside, the space is divided into 10 naves. Most agree it was some sort of giant cistern, built in the 1st century BC by the Roman soldiers who had come to conquer the Maremma and rule the Etruscans, which they succeeded in doing.
Who used the 4,000 cubic metres of water held in the cistern is anyone’s guess. To muddy the waters, locals believe the Bella Antiglia, an ancient Etruscan queen, is said to have been buried here, alongside her golden carriage and four golden horses.
Now back in the car and headed northwest. Follow the signs toward SR74 and after 8km turn left on Via Panfilo. On your left is Poggio Rota, our next stop.