Piscina Mirabilis: the underground enchantment of Bacoli

There is a wealth of evidence of the various peoples who found refuge among the gentle inlets of Campania. Those who left the deepest mark on this land were, without doubt, the Romans: an incredible people who scattered our territory with testimonies of their power.

We remember them for the speed, precision and skill with which they carried out, in ancient times, immense works that were utterly innovative for their era, such as the many aqueducts that carried water for miles and miles. One of the most majestic and astonishing of these works is found to the north-west of the Gulf of Naples, precisely in the town of Bacoli, and it is the Piscina Mirabilis. This is a water cistern, the largest ever built in Roman times, carved into the hillside that looks down over the port of Misenum, comparable in size and magnificence only to the one in Istanbul. It was built to collect water arriving from the "Fontis Augustei Aquaeductum" (the Fountain of the Augustan Aqueduct), that is, the Roman aqueduct of Serino, and to guarantee the water supply to the "Classis Praetoria Misenensis" (the Praetorian Fleet of Misenum), the fleet stationed at the port of Miseno (as well as to the town itself). Water was drawn through small wells at the top of the quarry using hydraulic machines that lifted it and carried it down to the port beneath the hill.

Inside the cistern

Once inside the quarry, you are left spellbound by the beauty of this place, which, with its rows of tall pillars and barrel vaults, feels more like a cathedral than a simple water tank. The interior, carved out of tufa stone, is 15 metres deep and could hold as much as 12,600 cubic metres of water. The space, laid out on a quadrangular plan, is divided into five long aisles and thirteen short ones, with four rows of twelve cross-shaped pillars supporting the barrel vaults. The inner walls are lined with "opus signinum", a mixture known today as cocciopesto, made of crushed brick and lime, which made the structure waterproof. Set into the floor of the central aisle is a piscina limaria (settling pool) which, measuring 20 by 5 metres and 1.10 metres deep, served as a decanting tank used to clean the cistern.

Because of its charm, the Piscina Mirabilis became a much sought-after destination for the Grand Tour, the journey that aristocrats of the age used to undertake during the Renaissance to broaden their knowledge. As proof of this, several inscriptions are carved into the walls of the cistern bearing witness to the passage of these young nobles, including Dumas, Goethe and Mozart.

Information
Address: Via Piscina Mirabile, 80070 Bacoli NA, Italy
 Opening hours: 09:00–18:00
Cost: free donation
Bookings: 081 523 3199 (caretaker); 0815235968 (Tourism and Cultural Heritage Office of the Municipality of Bacoli)
A booking is required in order to visit the Piscina Mirabilis.