Grotta Giusti Thermal Spa Resort

What to expect

Grotta Giusti is a five-star hotel and spa at the foot of the hills outside Monsummano Terme, in the Valdinievole between Florence and Lucca. It belongs to the Italian Hospitality Collection and is part of Marriott’s Autograph Collection. The reason to come is underneath the building: a natural karst cave full of warm, humid air and thermal water.

The cave runs for more than 200 m under the resort (Italian Wikipedia gives about 300 m) through chambers with stalactites and stalagmites. Tradition divides it into three zones that get warmer as you go deeper, named after Dante: Paradiso, Purgatorio and Inferno. The air rises from about 82°F28°C to 93°F34°C, and humidity is close to saturation. At the bottom lies Limbo, a clear thermal lake held at about 97°F36°C. Here the cave is used as a steam bath: you sit or lie in the warm air rather than soak in a pool. Certified divers can also book guided dives in the lake.

Above ground is the part most day visitors use: a 750 m² outdoor thermal pool with a waterfall, four “snail” hydromassage stations and 40 hydromassage seats. Next to it stands the Bioaquam Pavilion, a 310 m² covered relaxation area with sliding glass walls, a retractable roof and a heated floor, so the pool works in winter too. Indoors there are smaller pools, the Meditarium thermal bath, saunas, steam rooms and a large treatment centre. The Bioaquam Café serves light meals by the pool.

The water and the cave

The Grotta Giusti spring delivers bicarbonate-sulphate-calcium-magnesium water at 93°F34°C. The operator says it is used without chemical or physical treatment and piped straight from the source to the pools, the mud maturation tanks and the treatment rooms. The outdoor pool is kept at about 95°F35°C, according to Visit Tuscany, and the indoor Bioaquam pool at 93°F34°C.

The spa promotes the water and the cave steam for joint, breathing and skin complaints. Treat that as marketing; this guide makes no health claims.

History

Workers quarrying lime for Domenico Giusti, the father of the poet Giuseppe Giusti, broke into the cave by chance in the spring of 1849. Domenico had run the state baths at nearby Montecatini since 1818 and saw its value straight away. A small building with steam rooms went up in 1853, when the cave opened to the public, and a hotel followed in 1873. Garibaldi came in 1867. Giuseppe Verdi, also a visitor, called the cave the eighth wonder of the world, a line the resort still quotes. The spa was renovated in the 1970s, and the operator lists a World Spa Awards title for the grotto in 2026.

Prices and booking

Thermal pool, adults (2026):

• Weekday day ticket: €36
• Weekend, holiday and day-before-holiday ticket: €49
• Weekday afternoon from 2 p.m.: €29 (not on some peak dates, such as late April, June 1, and Christmas to early January)
• Children aged 5 to 11: half price

Multi-entry passes: 10 weekday entries €250, 20 for €420; 10 weekend or holiday entries €380, 20 for €700; 10 weekday afternoons €220. A 10-entry pass usable any day and shareable between people costs €400. Residents of Monsummano Terme get 30% off a day ticket, and groups of five or more adults get 10% off.

The cave: a 50-minute steam bath in the grotto costs €50. It is not included in a pool ticket.

Day spa packages combine the pool and the cave. “Acqua & Relax con Spa Lunch” is €100, with the pool, a 50-minute cave session, a robe and towel kit and lunch at the poolside café. “Thermarium” is €120, with the Bioaquam pool, steam bath, sauna, an ice waterfall, the cave and the kit.

Rentals: robe, towel and slippers kit €15; bathrobe €7; towel €5; slippers €3 and swim cap €2 to buy.

Booking is recommended, particularly for the cave and at weekends. Use the online booking system or call the spa on +39 0572 9077992 ([email protected]).

Getting there

The address is Via Grotta Giusti 1411, Monsummano Terme (province of Pistoia).

• By car: take the A11 Firenze-Mare motorway to the Montecatini Terme exit, then follow signs for Monsummano Terme. The resort is about 4 km (2.5 miles) from the exit.
• By train: the nearest station is Montecatini/Monsummano Terme, about 4 km (2.5 miles) away; take a taxi from there.
• By air: Florence Amerigo Vespucci airport is about 40 km (25 miles) away and Pisa Galileo Galilei about 55 km (34 miles).

When to go

Grotta Giusti is open all year. Winter is the best season for the outdoor pool: steam rises off the water, the Bioaquam Pavilion keeps you warm between dips, and the cave feels the same as it does in July. Summer afternoons can be uncomfortably hot for a 95°F35°C pool and a 93°F34°C cave, though the gardens are pleasant.

Weekdays are cheaper and quieter than weekends. The pool closes early on Wednesdays (6 p.m. until November 1, 2026, and 3 p.m. after that), and the treatment centre opens 9 a.m. to 7 p.m. Monday to Saturday and 10 a.m. to 7 p.m. on Sunday. In autumn 2026 the spa also ran Saturday evening openings from 7:30 p.m. to midnight on selected dates.

Rules and etiquette

• Swimsuits in all pools. Bring a robe and slippers, or rent them.
• Children may use the thermal pool; ask about the cave and spa areas before you book.
• Book the cave as a timed session. It is quiet inside: keep voices low.
• Shower before entering the pools, as in any Italian spa.

Where to stay nearby

The resort itself is the obvious choice if you want the cave and pools on your doorstep. Montecatini Terme, about 4 km (2.5 miles) away, is a historic spa town with a wide range of hotels at every price. Lucca, Pistoia and Florence are all within an easy drive for a day trip.

Safety notes

• Heat and humidity. In the cave you sit in near-saturated air at up to 93°F34°C. Keep to the session time, drink water afterwards, and leave if you feel faint.
• Health conditions. If you are pregnant, or have heart or blood pressure problems, ask the spa’s medical staff before using the cave or the hottest pools.
• Wet floors. Cave paths and pool decks are slippery. Wear slippers.

Nearby stops worth adding

Terme di Montecatini, the grand historic spa town next door, is a 10-minute drive. The same hotel group runs Fonteverde in San Casciano dei Bagni and Bagni di Pisa near Pisa. Further north, Bagni di Lucca has a small historic bathhouse with its own steam grotto.