Bath, Somerset

Bath earns the top spot because it packs almost everything a couple wants into a small, walkable centre. One thing worth knowing: you can't actually bathe in the historic Roman Baths — they're a museum — so the soaking happens next door at Thermae Bath Spa, whose open-air rooftop pool, fed by the same naturally warm mineral springs, is the signature couples' moment (a two-hour spa session is indicatively around £40 per person, with pricier twilight and treatment packages). Beyond the water, this is one of Britain's most beautiful cities: the Royal Crescent, the Circus, Pulteney Bridge and Bath Abbey are all a short walk apart, and the honey-coloured stone is famously photogenic at golden hour. Add strong independent restaurants and cosy wine bars and you have a weekend that flows without a car. It's the pick for couples who want spa relaxation alongside sightseeing; skip it if you're chasing wilderness or a bargain, as central hotels and spa slots get busy and pricey in peak season. For a first romantic city break, though, it's an easy recommendation.