Tuscany isn't just vineyards: this is the hidden gem most visitors miss out on

A heavy fog rests on the shoulders of Val d'Orcia's hills, completely cloaking the rolling green and hilltop villages visible from my window the previous morning. Thunder rolls low and loud as fat raindrops ripple the pool's surface, sending steam curling and dancing upwards into the storm. It'll soon pass, as early spring storms in this part of Tuscany tend to. I'm in no rush, though, happy to lounge about in my plush robe and slippers while Mother Nature does her thing outside. Pulling my robe tight, I venture out of my room and head downstairs, where breakfast is as casual an affair as I please.

Despite its five stars, Bagno Vignoni's Hotel La Posta is anything but pretentious. Original polished travertine floors in the lobby - mined from a now-closed local cave - are warm and lived in, and the Murano glass chandeliers are elaborate without any of the gaudy sparkle.

Even the food escapes pretence, with the courtyard's garden cafe, Il Chiosco, not above serving burgers and Caesar salad alongside hand-rolled pici pasta and carpaccio topped with shaved 60-month-aged Grana Latteria San Pietro. But it's the robe-friendly breakfast nook that really drives the relaxed feel of the property home.

Considered more a "home" than a hotel, the 35-room, family-owned residence exudes warmth. It's as approachable as nonna and nonno's house, and unironically decorated that way, too. Sitting areas populated with antique furniture and card tables coax guests from their rooms and into the heart of the property, while gallery walls proudly display sepia-toned family photos of past and present owners.

Michil Costa, the property's current owner, is flitting about breakfast in his flamboyant sports coat and royal blue cravat. He's here regularly, and he makes a point of conversing with each and every guest to add the ultimate personal touch.

As I sip on my morning caffe latte and tuck into sweet crema di nocciole slathered toast, the storm outside subsides. The calcium carbonate, iron and zinc-rich thermal pools are Hotel La Posta's highlight, said to have restorative properties for the skin, joints and muscles.

The Etruscans were the first to discover the Mount Amiata-heated waters some 2000 years ago. But, it wasn't until 1973 and the excavation of the ex-postal store and vineyard, that La Posta capitalised on the warm volcanic waters flowing beneath the property, building the first pools of their kind in Val d'Orcia. I shuffle towards them in my slippers, parking up on a sun-drenched bed with views of the valley and hilltop medieval suburb, Rocca D'Orcia. Barely a cloud hangs in the sky post-storm, the springtime sun like a warm hug on my bare skin.

It's warmer still in the water, the top pool's resting temperature a comfortable 38 degrees. As the days in the valley heat up, the lower pools become more attractive, the water temperatures dropping the further you get from the source. Just a handful of people are out enjoying the thermal spa, their low conversation, the chirping birds, and the gentle splash of the spring water, the only sounds hanging in the air.

It's a true pleasure unwinding somewhere so peacefully devoid of rumbling freeway traffic and wailing sirens. Noise pollution is almost unheard of in Bagno Vignoni, the tiny village of just 30 permanent residents. The town centre is mere steps from La Posta's lobby, its entrance marked by a cobbled pedestrian street and the umbrella-ed alfresco of La Bottega Di Cacio.

Couples sit beneath the canvas, sharing glasses of red and small platters piled high with regional specialties like salame di Cinghiale - a salami of wild boar and pork - and Pecorino Valdorcino. Above them, vocal swallows dance and dive, ducking in and out of the village's heart. They're headed towards the deep, rectangular thermal pool around which the village is built.

No other town square in the world has a public bath at its centre like Bagno Vignoni. It has remained essentially unchanged since the 1600s. Now, the bath is under UNESCO protection and swimming in it is strictly prohibited. Though it's not open to swimmers anymore, it still plays a vital role in the village aesthetically. Lively cafes overlook the jade water, patrons flicking through books and sipping espresso in the morning sun.

Fed by the same springs that fill La Posta's pools, the natural baths are rich in calcium carbonate, large deposits of which create a lunar-esque landscape around the warm waters. A swimsuit-clad lady crunches her way down the rocky path, headed towards the last of the pools for a dip. Though it's free and open to the public, she's alone in her mission, most people opting for a day pass to the more luxurious pools of La Posta.

With slippers and robe back on, I pad down to a poolside sunbed. I waste no time wading into the pool, surrendering to its therapeutic properties. In a tiny Tuscan village where the slow life is the only way of life, floating here, in the warm water, is the ultimate state of being.

The writer was a guest of La Posta