Across the road is the Tower of London, where traitors and heretics once met an excruciating end on the rack. Here, in the Espree Health Club, the instruments of torture are more sophisticated: rowing machines, chest presses, triceps extensions.
This is the fitness industry in the late 1990s. Fifteen years ago, choice was limited to spartan gymnasiums run by local councils, over-chlorinated swimming pools or the private tennis clubs found in snooty suburbs.
The explosion of private gyms and health clubs has changed the face of keeping fit. There are now more than 2,000 centres, accounting for an industry worth pounds 1bn a year. In a report published this week, Greig Middleton, the City stockbrokers, forecast that another 300 centres will open in the next three years.
It is all very different to the days when exercise meant a round of circuit training or thrashing out 20 lengths in the pool. In modern clubs, you can work out on state-of-the-art equipment, attend an aerobics class, take a sauna and finish off with a massage and facial, all in spotless and pampered surroundings.
You will also pay through the nose for it. At the swanky Chelsea Harbour Club - once frequented by Diana, Princess of Wales - members pay pounds 2,700 to join and then an annual fee of pounds 1,250. The club was sold yesterday for more than pounds 22m.
Even the more down-to-earth establishments do not come cheap. It costs up to pounds 100 to join one of the popular no-frills clubs in the Fitness First group, and then pounds 30 to pounds 40 a month in membership.
Nevertheless, private gyms are big business. What started as a "yuppie" fad in the 1980s - when a well-toned body went with a power suit and mobile phone - has entered the main stream. The fitness culture has taken root in society. Belonging to a gym is a lifestyle statement.
Many large companies provide a health club, while others pay or subsidise membership for their employees. One of the most lucrative areas of the market is women-only gyms.
Even overfed politicians are starting to see the light. Recently opened in London is The Club at County Hall - located across the Thames from Westminster. Open 24 hours a day, it offers valet parking and is perfect for pumping iron after a late-night vote in the Commons.
But the origins of the industry lie in vanity, not health. In America, it all started on Muscle Beach in California, where steroid-laden Adonises performed weight-lifting exercises for an admiring audience.
In Britain, too, in the early days, working out equalled men lifting large chunks of metal. Jane Fonda, the aerobics queen, changed all that - making dance studios into unintimidating places and sparking the mass entry of women into the market.
Then, about 12 years ago, came the arrival of the cardiovascular machines that are the mainstay of today's clubs - a key development, since they removed the necessity to expose one's physical limits to others in a group situation. They meant that you could get fit on your own, at your own pace.
Peer pressure, with a dawning realisation that a flabby body is not an asset, account for the fitness craze of recent years. And by paying to join a club, people found convenience of location and longer opening hours than at their local sports centre.
They also managed to avoid the noise and bustle of children, although one of the most successful chains, founded by the former tennis star David Lloyd, is aimed at the family market.
Laurence Akin, managing director of Holmes Place, a leading operator, believes the social side is a big draw. "It's the feeling that you've joined a club, as opposed to simply working out," he said. "A lot of friendships are forged in our club rooms."
There is still a great deal of scope for expansion. Sarah Williams, of the Health Education Authority, says that, even now, only 40 per cent of men and 30 per cent of women take enough physical exercise. She points out, though, that upmarket gyms are beyond the financial reach of most of the population.
The technology has not altogether banished the macho spirit of competition that spawned the fitness boom. "I suspect that some men just come here to show off their muscles," said Joe Baker, 46, mopping his brow after a punishing session at Espree yesterday.
"Look," he said, pointing to one glistening young buck lingering in front of a mirror. "I bet that one doesn't half think he's gorgeous."
Business, page 13
The number of fitness clubs in the UK has grown from 1,960 in 1992 to 2,200 in 1997, according to Mintel, the market researcher.
Investment in the sector over the next three years could reach pounds 750m, analysts predict. That could translate into 300 new clubs and 750,000 new members, according to Nick Batram, a leisure analyst at the stockbroker Greig Middleton.
The gym and health club business is now worth pounds 1bn a year, a 58 per cent increase in five years.
Two million people were members at health clubs last year compared with 1.6 million in 1993. One in three adults would like to join a club, says Mintel.
David Lloyd Leisure, the chain started by the former tennis player, was worth an estimated pounds 30m in 1993. In 1995 Whitbread bought its 13 clubs for pounds 200m. The chain now has more than 20 clubs and 100,000 members.
The average cost of annual membership of a club last year was pounds 340.Reuse content