Californian Solage Hotels & Resorts has completed a multi-million renovation of its Spa Solage at the flagship Solage Calistoga property as part of a US$2.3m (€2m, £1.5m) capital investment.

The 14-treatment room Spa Solage has been expanded as part of a four-month project led by San Francisco-based interior design and finishes specialist Shirley Robinson, principal of Robinson Finishes. The 2,500sq ft (232sq m) expansion to the reception building includes a new indoor and outdoor relaxation lounge, expanded male and female locker rooms with outdoor showers, an enhanced menu of services and fitness programmes, plus a redesign of the overall interior decoration.

“My inspiration behind the design at Spa Solage was to create an atmosphere reminiscent of slipping into an extravagant white terry cloth robe – it’s a luxuriously comfortable experience,” said Robinson. “We featured white and silver tones throughout the space to convey a fresh, crisp, clean look that’s chic and sophisticated.”

There are white capiz shell walls in the new 1,400sq ft (120sq m) mixed gender indoor/ outdoor relaxation lounge, custom-made furniture, white marble floors and white hand-troweled Venetian marble dust plaster waxed walls within the spa, as well as new outdoor showers.

A new herb garden showcases vegetation from Calistoga, such as rosemary, French lavender, California white sage and mint – each of which is used in the spa’s offerings.

Existing facilities at the 89-bedroom hotel’s 20,000sq ft (1,858sq m) spa include a bathhouse with geothermal soaking pools, a gym and a fitness studio.

Products on offer at the spa, for retail and for treatments include those by Epicuren, Scientific Organics and True Nature Botanica. The NuFace Trinity device will also feature at this site. In the resort’s spa boutique, ‘Spatique’, skincare will be sold alongside activewear for women by Lole and activewear for men by Qor.

The resort is located on 22 acres (9 hectares) of land surrounded by panoramic mountains and vineyards. It has a Michelin Star-rated restaurant called Solbar led by the brand’s vice president of culinary services, executive chef Brandon Sharp and it also has a 130ft (40m) swimming pool.