The vast Széchenyi Baths might be the best known in Budapest, but the Rudas Baths have a contemporary spa too (stay at Pest-Buda, which has doubles from around £127). A visit is based around the 16th-century Turkish bath (some weekdays are single-sex only, so check the timetable first), but there are also a series of thermal pools, including one on the rooftop with sensational Danube and cityscape views. Massages start from £20 for 20 minutes; on Friday and Saturday evenings night bathing sessions until 3am take a more sociable, party-like turn.
Website: rudasfurdo.hu
The Well, Oslo, Norway
Price: From around £170 per person, per night
Just 15 minutes from the centre of Oslo, this is the largest spa in Scandinavia, which means a seriously impressive hot-cold circuit that takes its cues from bathing practices around the world. There are nine saunas – including a Northern Lights laconium, a meditation sauna and a forest sauna overlooking the trees – four jacuzzis, a cold plunge, a cave-like hot spring bath and an Art Deco tepidarium with a gold-plated bench, plus much more. Keep an eye on the daily timetable for the German Aufguss ritual (where the sauna master places essential oil-infused ice balls onto the stove and pours water over them, fanning the air to increase the temperature and humidity) and the Moroccan Rhassoul ritual involving a body scrub and clay mask (around £15).
Website: thewell.no
Longevity Health & Wellness Hotel, Algarve, Portugal
Price: Doubles from around £112
Put a wellness spin on a stay in the Algarve at this health-focused hotel in Alvor. When you’re not beach-hopping (the main stretch of golden sand is an eight-minute drive away), head to the spa’s “detox and relax” circuit, which includes an infra-red sauna, Epsom salt room, a pair of heated pools and walking paths. The Pure Café restaurant serves up vegetarian, gluten-free and high-protein food for dinner, and guests can join in the daily group activities, ranging from yoga and pilates to core training. Add on body scrub and bath rituals, natural clay therapies, seaweed wraps and drainage treatments, for under £100 each.