No one would go there willingly at night and on foot, but that is what many motorists are forced to do as part of their punishment for being clamped. It is almost as hostile by day - but then there are more likely to be other motorists in the same predicament. For anyone wanting to be unclamped after midnight in London, there is no choice but to face this tunnel of despair.
The journey begins on the pavement beside Speakers' Corner, by the Marble Arch roundabout. The tunnel, designed for cars, has no proper pavement at its entrance, so pedestrians must take a risk and walk in the roadway. Taxis are now allowed down the tunnel but confusing notices at the entrance deter them and most are unwilling to go down.
The tunnel, lit by harsh strip lights, sinks rapidly downwards and then bends so a car may approach rapidly without being seen by pedestrians. Nevertheless, the approach of traffic can scarcely be mistaken. Any noise in the tunnel is magnified as if it were a gigantic organ. Hearing the roar intensify, the pedestrian who has reached the second part of the tunnel may duck under a railing to reach a pavement.
But there is still another 150 yards (137m) to go past the black wire car pound and gates secured by large padlocks before reaching the police bunker, where the payments are made. Motorists must then return to their cars and wait for a mobile clamping unit to free their vehicles.
Last week the Independent spent three hours in this dungeon talking to luckless people who came to get their cars unclamped. The first to arrive, just before midnight, were three young London women who talked as they came down the tunnel with the sort of ready cheeriness reminiscent of a trip on a ghost train.
Penella Davis, 24, had parked her Montego in Beak Street while she went for a drink in a wine bar with friends, Sharon Buchanan, 22, and Donna Henry, 24. 'I have got to get the car back. It belongs to my brother,' she said. 'I wouldn't want to come here by myself - it's really frightening.'
With a roar a taxi came down and deposited Lynn Turner, 28. She had made the mistake of leaving her car in residents' parking beside Cranks restaurant, in Soho, not realising that Westminster has a new rule that parking is restricted until 10.30pm.
The last 70 yards to the police bunker is blocked off to vehicles and so Ms Turner had to walk. As she did so the taxi manoeuvred round a van, which had just arrived, making a three-point turn so he was ready to escape from the tunnel. A series of bollards which seemed to serve no purpose made it impossible to complete a straightforward turn.
The cab driver said: 'It's a complete mess here. It's like an obstacle race. We used to be allowed to come down and turn. Then they stopped it. Now we are allowed down again but we can't turn. It doesn't make any sense. There must be some ignorance in the hierarchy because it doesn't have to be like this.
'I've lost count of the number of people I have had to direct to the pound. It's not clear which way to go. I had a disabled passenger the other day. He could hardly walk and I couldn't help him. He had to shuffle to the clamp office and back. He was exhausted afterwards.'
Through the night car owners of all ages and classes came and went in the Park Lane pound, which has been used by the police since 1979. People used to the protection of their cars are forced into a hostile environment, and if they leave by another exit to Park Lane are forced to pass through a maze of dreary tunnels populated by dossing beggars.
Chief Superintendent Kevin Delaney, who is in charge of the Metropolitan Police traffic branch, said: 'We have known for some time that the Hyde Park payment centre is not satisfactory. I certainly wouldn't want my wife to go down there. It is nothing more than a hole in the ground.
'We are looking for something less menacing, an ordinary shop somewhere in the centre. We thought we had found a place near Victoria, but we were unable to obtain planning permission for a change of use.'