Today, Count Benedikt Bolza is the proprietor of the 3,700-acre Reschio estate and hotel on a hilltop near the border of Umbria and Tuscany. Forty years ago, he was a 10-year-old on a road trip from Munich looking for a vacation home with his father, a nobleman of Austro-Hungarian descent.

They found San Martino, a tumbledown former rectory with a bell tower and chapel, and were so enamored with it that they made it their permanent home.

It was only later, when the family tried to buy some neighboring land, that they discovered it was encased within the Reschio estate, originally built as a defensive fort in the days when feudal wars raged throughout Umbria’s undulating patchwork of hills and valleys. Ultimately, they acquired the entire parcel, which came with its own crumbling castle. After a decades-long renovation, it recently opened as a 36-room hotel.

Top, Count Benedikt Bolza agonized over every aspect of the interiors; above, the dramatic entrance to Ristorante alle Scuderie, which serves classic Italian food.

“Everything was wild and abandoned,” says Bolza, who studied architecture in London. Upon his return to Italy, his first task was to assess the 50 dilapidated homes, once inhabited by tenant farmers, that were scattered throughout the grounds. And so began a process of building-by-building restoration, enacted over three decades. Today, those homes (including San Martino) are available to rent or even buy.

Bolza lives on the estate with his wife, Donna Nencia, a decorative artist and member of Florence’s Corsini dynasty. The couple met in 1999, when Nencia was hired to paint frescoes in one of Reschio’s buildings. They have five children and have transformed the castle from a leaky-roofed vault for farmed crops into a ravishing and refined home.

Sit back and relax: at Reschio, the real world seems very far away.

In 2007, they downsized to a smaller home on the estate and began transforming the castle yet again.

Bolza masterminded its design from his hangar-like studio in a former tobacco factory at the foot of the hotel. “We wanted it to feel as though we’d never left,” he says.

Every room takes an ancestor or family friend as its starting point, and the décor combines inherited artifacts and antiques with portraiture. The palatial Room 8 is especially striking. It has a gilded altarpiece above a desk of Bolza’s design, and its four-poster bed is hung with an embroidered crimson panel.

Instagrammable moments are everywhere.

At Reschio, Bolza’s signatures are everywhere—in the frescoes in the chapel, the scarlet “CdiR” (which stands for Conte di Reschio) monograms cross-stitched onto every pillowcase, the bespoke furnishings, even the jewel-colored paints made from natural pigments. The lighting is low (a rarity in Italy) and flattering, and no electrical wires are ever displayed. (Even charging ports are shielded from view in leather boxes.)

Days at Reschio are relaxed and luxuriant. Those who tire of the serene pool can venture to one of the lakes for a picnic and swim. Yoga classes are held in the converted chapel, and tennis and horseback riding are also tempting. (Reschio’s dressage arena was built for the estate’s 40 purebred Spanish horses.)

Bolza’s signature touches include the scarlet “CdiR” (which stands for Conte di Reschio) embroidery.

The original stables have been transformed into Ristorante alle Scuderie, where classic Italian food is served among towering fern trees on a terrace that overlooks the estate. For a more intimate and formal experience, try dinner in the castle, where the dining room is beautifully lit by Bolza’s 30s-style Poggibonsi table lamps. In the cooler months, slip next door for a nightcap in the old kitchen, next to the open fire.

The jewel in Reschio’s crown is the Bathhouse, a grotto spa with Roman baths that is overseen by Nencia. Massages and facials are administered near an open fire to the sound of Gregorian chants.

Not pictured: the dressage arena, built for the estate’s 40 horses.

For centuries, the Reschio estate was primarily populated by wild boar, roe deer, and the occasional wolf. In its next phase, it will be frequented by some of Europe’s most stylish travelers.

The writer was a guest of Reschio, where room rates start at $925 per night, inclusive of breakfast. A two-night minimum stay applies

Aimee Farrell is a Cambridge, U.K.–based writer. She is a contributing editor at the Financial Times’s HTSI and a contributing writer at T: The New York Times Style Magazine and British Vogue