There were five of them, not four, and they weren't that fab yet, when in 1960 an obscure English band called the Beatles arrived in Hamburg.
When a battered minibus carrying John Lennon, Paul McCartney, George Harrison, Stuart Sutcliffe, Pete Best and four others chugged into Hamburg, the not-so-fab-five entered an alien world.
The English city of Liverpool where they came from was also a port with its rougher sides, but Hamburg's infamous red light district set new standards in seediness that were enough to make all but the toughest docker blush.
The band, hired by a club owner with a limp called Bruno Koschmider, were on contract to entertain guests in a moth-eaten strip joint known as the Indra. First taking to the stage on August 17, 1960, Koschmider told the boys to "mach schau" or "make a show".
Horst Fascher, the former boxer who would later get the Beatles to play the nearby Star Club, said he saw them on their second night with a large group of male and female friends, and to his disgust found them playing skiffle.
"After half an hour I said to my friends, let's go back to the Kaiserkeller for some rock'n'roll," he told AFP, adding with a knowing wink: "But the girls, they didn't come ... The girls said 'they look good'."
And the Beatles soon got a lot better, belting out rock'n'roll covers and increasing their stamina with the help of German lager and drugs to keep them going.
"We really had to hammer. We had to try anything that came into our heads," Lennon recalled later. "We played what we liked best, and the Germans liked it as long as it was loud."
Working so hard -- the record was 98 nights in a row -- is widely credited with creating the foundations for their prodigious talent that would later make them world-famous.
"I might have been born in Liverpool, but I grew up in Hamburg"
Off-stage, life in Hamburg was also a highly formative experience for the Beatles, with the area where they played and lived offering the teenagers -- all were under 20 in August 1960 -- a world of opportunities.
At first Koschmider put The Beatles up at the Bambi cinema, a stone's throw from the Indra that showed a mixture of porno movies and westerns, forcing them to sleep in a windowless room with no toilet and no heating.
"They stank of sweat, and sometimes from old sweat from the day before," Fascher told AFP. "I took their underwear and gave it to my mum to boil-wash."
Having girlfriends back home didn't stop the band taking advantage of the many female admirers who threw themselves at the English boys playing the funny music, although their cramped living conditions meant privacy was at a premium.
Harrison, just 17 when he first arrived in Hamburg, is reputed to have lost his virginity there, with McCartney, Lennon and Best clapping and cheering when it was over.
During one of their spells in Germany, another English band on the bill -- Rory Storm and the Hurricanes -- had a certain drummer going by the name of Ringo Starr, and it was in Hamburg that they first played together.
Pete Best's days as the band's drummer were numbered. Back in England soon afterwards, he would be unceremoniously booted out the band.
"When there were the four of us with Ringo, it always felt rockin'," Harrison is quoted as saying.
The Hamburg period is also tinged with tragedy because it was also where Sutcliffe, another "fifth Beatle", died in April 1962 from a cerebral haemorrhage, just before their inaugural concert at the Star Club.
All things must pass
The band, which in five separate periods between 1960 and 1962 played in the Indra and three other clubs: the Kaiserkeller, the Top Ten Club and the Star Club, all in the same Reeperbahn district still full of sex shops to this day.
Today, only the Indra and the Kaiserkeller are still concert values. The Star Club, which was also played by Jimi Hendrix, is no more and the Top Ten, although a club, is unrecognisable.
The building which housed the Bambi is still there, but it is no longer a cinema, with a small sign informing passers-by of its famous former residents.
Until recently, this was practically the only sign in Hamburg that the Beatles had ever been in the city apart from the re-naming of a square as Beatles-Platz with some abstract statues of the band including Sutcliffe.
The new museum, which opened on Friday, is meant to change all that.
Set out over five floors, it tells the story of the band from Hamburg to their break-up, with interactive exhibits like a mock-up of the legendaryAbbey Road studios where visitors can record themselves singing.
There are also hundreds of photos, including some rare ones from their Hamburg period, as well as artefacts ranging from a postcard from Starr back home to memorabilia from the height of their fame.
Sticking out of the front of the building is a huge, inflatable yellow submarine, and downstairs there is a fish and chip shop -- for Germans the height of Englishness. The name? "John & Paul's."
"This museum reminds me of the old days and sometimes it hurts," Fascher said. "I had a good time, I was a lucky man."