Despite India's economic success, it is still home to millions of the world's poorest people. Martin Buckley lived in Bombay, as it was known, in the 1980s. He recently went back and found, as he walked about after sunset, that the essential character of the city remains unchanged.
Mumbai: Twenty million people live in India's most populated city
Bombay by night. It is hard to think of three words more expressive of history, exoticism, and empire.
And I do not begrudge the "new" name, Mumbai (the city was renamed in 1995).
The city's presiding goddess is Mumba-Ai, and I spent a chunk of the 1980s living close to her temple in the heart of the city.
It was my first job after university, working on a magazine called Business India. Very few foreigners worked in Bombay then.
Pre-boom India was still locked into its Soviet-style command economy.
Paid local rates, I lived in a succession of seedy rooms in downtown Bombay.
We sometimes put the magazine to bed at 0300 local time, and I would walk home.
On the pavements were string beds, where men lay, totally abandoned in sleep.
I never felt threatened for an instant.
We have heard a lot lately about Mumbai's slums, so I thought it would be interesting to revisit my old haunts.
Dharavi is Asia's largest slum spanning more than 500 acres
Mumbai is a long, thin city, and on its northern fringes, residential suburbs are mushrooming.
I went to visit Dharavi, the slum made famous by the film Slumdog Millionaire, which is nearer the city centre on land the developers would love to get their hands on.
This "slum" has electricity, workplaces, temples and mosques.
I asked a street trader selling school exercise books if he had heard of Slumdog Millionaire.
"Of course," he said, adding that tourists had been turning up in droves to see where the film was shot.
But he said they should go home, as no-one wanted them there.
I felt no danger in Dharavi, at least, not from people.
Stepping on a sleeping dog - an actual "slum-dog" - was far more of a worry.
The next night, a hot, sticky evening, my first stop was at a downtown police station in central Mumbai, to interview a police inspector.
The Oscar-winning film Slumdog Millionaire highlighted the city's slums
He was a sleek character, with manicured nails, dyed hair and an expensive-looking Swiss watch.
Sipping sweet tea from an improbably refined china cup, I sheepishly asked about the brutal police torture shown in Slumdog Millionaire.
"Ridiculous," he replied, though he did admit that what he called "light beatings" were routine. And no, I could not visit the cells.
He moved hastily on to more comfortable territory, showing me his CCTV screens, and declaring how modern forensics had transformed criminal investigation.
His biggest task, he stressed, was managing tensions between Hindus and Muslims.
Doggedly, I asked about police corruption and drugs mafia, but received peremptory replies.
Prostitution he claimed, was sharply down, but not through policing. Rather, he claimed it was because people were terrified of catching Aids.
Physically, central Mumbai has changed far less than I expected.
There are some elevated highways from which, I am told, motorcyclists periodically plunge.
The markets and dockyards of Mumbai are still thriving
But the great tenements still rise in terraces draped with washing, their Victorian or art deco facades slowly decomposing.
Few of the 1960s-style Fiat taxis have been replaced by newer cars.
There are bullock carts toting jute bales, tiny shops with colonial interiors, hawkers selling fruit from trolleys, men sitting cross-legged in the street selling shoes, basket-weavers working and living on the pavements.
Markets sell everything from metal ware to fresh fish, and as 2200 approached, I could still see live mullet writhing in baskets.
Nearby were the entrepots of Mumbai's thriving dockyards, with the seedy, raffish air of a Conrad novel. And it is much easier to buy a beer in contemporary Mumbai than it was in my day.
Religious tensions have worsened, but I passed Hindu and Muslim traders working side by side.
Decay and ambition
In Bhuleshwar, in the old heart of Mumbai, I visited the city's presiding Hindu goddess.
The pillars of Mumba-Ai's tiny temple were entwined with flowers to resemble an indoor forest, and people urgently jostled for a glimpse of the deity.
By midnight I had reached Falkland Road, Mumbai's infamous red light district.
Women stood around gloomily, their faces showing none of the flirtation that is supposed to be their profession's stock in trade.
Mumbai's sex industry caters to millions of poor men, and its squalor and joylessness are all too evident.
A pimp was hanging onto my arm. I asked him if it was true that client numbers were down. He became aggressive. Was I there to spend money or ask nosy questions?
I flagged down a taxi, and slid on to the back seat. Through the open window, the air was now pleasantly cool.
The essential character of the great city I had known and loved 25 years ago, seemed to me unchanged, and it was still a Dickensian canvas of decay, ambition, and exploitation.
But Mumbai is pragmatic. It looks chaotic, but it works.
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