A dusty pot-plant sits in a deserted reception area, and pieces of mail lie around unopened, addressed to assorted "import- export" businesses. Down the street tourists stare in shop windows, admiring the finesse of the Antwerp diamond "cut", or take a coffee in the Jeruzalem Restaurant as Daimlers glide quietly by.
A buzzer suddenly opens a glass door, leading to a lift. Sunflower seed shells scrunch underfoot. I have already been told that Mr Brandwain likes to chew sunflower seeds. I have also been told that this Ukrainian-born "businessman" is Antwerp's gangland boss, and that the Antwerp connection to the mobsters of Moscow used to lead right here, to 26 Heren Street, until the recent turf wars meant the Antwerp connection was squeezed.
Over at the Antwerp police headquarters, Guy Janssens, the senior commissioner investigating Antwerp's organised crime, is hard on Mr Brandwain's heels, watching for the slightest slip. Mr Janssens, clearly the hard man of the Antwerp vice squad, is a man of few words, saying only that Mr Brandwain has "some weird kinds of friends". Then he pauses and adds: "You will appreciate why I can't tell you more."
But in New York, the FBI and the Drugs Enforcement Agency have files on the Brandwain organisation, which link it with one of nine core Russian mafia groups in the world. And Israeli intelligence are watching him too. Mr Brandwain's former partner, a New York mobster called Boris Nayfeld, is awaiting trial in New York, for drug trafficking. And before he was arrested in New York last spring, Vyacheslav Ivankov, the Russian "godfather" of Long Island's Brighton Beach, is said to have issued threats to Brandwain of the kind which nobody can ignore.
Mr Brandwain is expecting me. I had called him earlier on his mobile phone, and he must have seen me walk in on the security screen on his desk, because he is waiting in jeans and open-neck shirt at the door. A stocky, fair, thick-jawed man of 47, he is faintly pink in the face after a week in the Tel Aviv sun. He doesn't like journalists, he exclaims immediately. They all write "criminal bullshit". But he turns down the volume on CNN, pushes back a rack of telephones, offers me a coffee and seems happy to talk all the same. Behind the desk is a picture of Mr Brandwain offering a donation to the Lubavitcher Rabbi in New York. Those were evidently happier days, when business was good.
For now, Mr Brandwain is just keen to protest his innocence, and to explain how he became a victim of the Russian mafia. He was never a part of it. The new mobsters - those who were let out of the "zoo", as he calls Russia today - have moved in on established "legitimate" Russian businesses like his. Mr Brandwain deftly cuts and polishes the story as he goes, pausing only to issue orders down the telephone in Hebrew, or flick through a stack of faxes.
Rachmiel Brandwain - known here as "Mike" - was born in the Ukraine and raised in Israel, where his family emigrated in 1959. After serving in the Israeli merchant navy, he decided to come to Europe to start a business, and Antwerp was an obvious choice. The city, in the heart of Europe, has a well-established Russian community and a thriving port, where 3,500 containers are unloaded each day.
He started with a small textile and electronics import-export company in Pelikan Street, alongside the railway line, but quickly moved into international trade. Mr Brandwain's particular financial expertise led him successfully to exploit the new markets of eastern Europe, making millions selling electronics to the Soviet army in Germany, through his fast-growing company M&S International. The methods he was establishing followed the patterns being established in other Russian emigre communities in New York or Tel Aviv. But Mr Brandwain was better than most, and established a trading hub in Berlin, before moving worldwide. Apart from one arrest for gold smuggling in 1986, he kept largely beyond the law.
Mr Brandwain's troubles began in the late 1980s. When the Berlin wall came down, he looked for new business in Russia and fell in with the vory v'zakone, or "thieves in law", as the organised Russian mafia bosses are known. He took on Boris Nayfeld, a big-time mobster and ex-wrestler, as a partner in M&S International. Nayfeld began cultivating new "clients" in Russia, and the M&S networks provided ready-made routes for trafficking in heroin and cocaine, with shipments passing through Singapore, Bangkok, Antwerp and New York.
Mr Brandwain says today that he knew nothing of Nayfeld's drug trafficking. He was "surprised" when his partner was arrested in New York two years ago, and insists that they parted company as soon as he suspected that Nayfeld might be using M&S for criminal activities. "Now I know what he has done I wish him to stay in jail for 200 years," he protests. "He just came to me. He was introduced to me. When you are a successful businessman people come to you, like a mosquito to a swamp. Sometimes comes a good mosquito - sometimes bad. He told me he could introduce me to people in Russia."
In a short time, M&S had nine shops in Russia, and Mike Brandwain believed he had made it into the big league. Then his "clients" turned on him, first offering "protection", then tightening the screws. "They wanted to take my business. They told me: `We are the bosses, not you.' They said I should go away. And I should be happy to go away alive. So I left. I am not a coward - but I was alone. I am innocent. The police can talk to me whenever they like."
Mr Brandwain says he has lost $15m in investments to the Russian mobsters, who just took over his shops, which is why his company is bankrupt and the building "to let".
His fate is being awaited with keen interest in Antwerp. Will his protestations of innocence keep him out of jail? Will Chief Inspector Janssens keep Mr Brandwain sweet, in the hope that he might help entrap the bigger fish? Mr Janssens and police colleagues all over the world know that the fast- spreading operations of the Russian mafia are now running well beyond their control. Down on Pelikan Street, where Mr Brandwain cut his teeth, the older Jewish diamond traders nod knowingly at mention of his name. "Mafia - who knows?" said one Russian trader. "He was like this all the time," he says, snaking his hand along the table. "Impossible to catch."
Mr Brandwain himself seems confident that the police will never nail him. He has even set up a new "import/export" business and is still fighting to get his money back from the "criminals" who took it. "The police have no evidence. Why don't they arrest me if they want to? I will talk to Mr Janssens any time," he says.
Whether he is confident that his old "clients" will leave him alone, however, is less sure. "People say I have to watch my back, but that's bullshit. I am not afraid," he insists. "For those criminals in Russia the only answer is another Stalin. They should be closed in their zoo."