Bath is first and foremost a Georgian city, but its newest attraction is founded on impressive Victorian engineering. Last Saturday, Combe Down Tunnel – bricked up since the closure in 1966 of the Somerset and Dorset Railway – opened with great fanfare to cyclists and walkers.
Burrowing through the hills south of Bath, the tunnel is just over a mile in length, and as such, it is being trumpeted as Britain's longest cycle tunnel. Riding through the underground thoroughfare is a striking sensory experience. The tunnel curves at both ends, so there is little daylight inside. Instead, lights placed every seven metres cast soft pools of illumination on to the smooth road surface and the sooty brick and limestone walls. So as not to disturb the resident bats, the low roof of the tunnel is kept in semi-darkness. Halfway along, you hear violins playing. An acoustic trick, you wonder. But no: the music is in fact coming out of speakers set into recesses.
The transformation of the tunnel from the days when trains huffed and puffed on their way from Bath to Bournemouth is remarkable. While the air inside now feels pleasantly fresh, that used not to be the case. Combe Down was the UK's longest railway tunnel without intermediate ventilation. "Riding on the footplate through the tunnel was terrifying," says John Sawyer, a Somerset and Dorset Railway fireman who attended the opening last weekend. "I'll never forget the heat, the steam, the smoke."
Combe Down Tunnel is, in fact, just one element of the new Two Tunnels Greenway, a four-mile-long cycling and walking path along the single-track section of the Somerset and Dorset Railway that ran from Bath to Midford south of the city. The project has taken seven years of planning and three years of construction work, and cost £4.3m in funding from Sustrans (via the Big Lottery Fund), the Department for Transport, the local council and other donations. It is, in other words, a very big deal for little old Bath.
I tried out the route on my bike on its opening day last weekend, starting off at the Bath end. The first section – which commences where Bellotts Road crosses the Bath-Bristol railway line – is Linear Park, a smooth lane that passes the backs of Victorian and modern terraces in the suburbs of Twerton and Oldfield Park, and crosses two newly installed, handsome and green-painted steel bridges.
After a mile, you reach the other of the two tunnels to have been reopened: Devonshire. A quarter of a mile long, it offers a similar, though briefer, experience to the Combe Down Tunnel. You emerge from Devonshire Tunnel into Lyncombe Vale, a secluded wooded valley on the city's fringes, then soon disappear underground again into Combe Down Tunnel. When you reappear into the open air, you are out of Bath, in glorious, rolling countryside. After crossing Tucking Mill Viaduct – another of the Two Tunnels' major restoration projects – look out for Midford Castle up on your right. Until a few years ago, the castellated, Gothic home was owned by the actor Nicolas Cage.
Just beyond is the end of the Two Tunnels Greenway. You could refuel at the pleasant pub here, the Hope and Anchor, before retracing the route. But you should also bear in mind that the Two Tunnels path has created a brilliant new 13‑mile cycling loop out of and back into Bath.
Just before the Hope and Anchor, look out for the sign to Monkton Combe on National Cycle Route 24. Follow the quiet back lanes to and through the village, and in about 15 minutes you're off the road again on the towpath of the Kennet and Avon Canal, part of National Cycle Route 4. The stretch of canal back into Bath is lovely. You pass Dundas Aqueduct, a fine piece of 18th-century architecture spanning the River Avon, then make a leisurely arc through a pretty, rural valley (I spotted a heron in the reeds) to Bathampton, where the almost-waterside George Inn is a convenient pit stop.
Ten minutes on lies Bath, where you can continue cycling along the canal as it cuts elegantly through Sydney Gardens, then Widcombe. Or you can stick to cycle route 4 on roads through the city centre, down Great Pulteney Street, past Bath Abbey and out by the riverside cycle path that continues on all the way to Bristol, and passes close to the start of the Two Tunnels Greenway.
Sustrans predicts the Two Tunnels path will attract one million journeys a year made by locals and visitors to the city. Based on the thousands of cyclists, and walkers, who turned out on the opening day last Saturday, I suspect that may be a massive underestimation.
Quirky, with no roads to cross, and, thanks to those tunnels, very gentle gradients to tackle, the eight-mile, there-and-back cycle ride along the path is an ideal outing for all the family. The 13-mile circuit out of and back into Bath that the Two Tunnels path has now made possible is even more enticing, and must offer one of the most scenically varied and sightseeing-rich couple of hours of cycling anywhere in Britain.
Bath Spa (08457 48 49 50; nationalrail.co.uk) is the city's main station, but First Great Western trains also stop at the Oldfield Park station, which is much nearer the start of the Two Tunnels Path (about 250 yards away).
If you're planning on doing the 13-mile loop, the most convenient bike rental outlet is at Bath & Dundas Canal Co (01225 722292; bathcanal.com) at Brass Knocker Basin, just before Dundas Aqueduct. Rental from £8 for one hour and £18 for a full day.