The Paris-Opera is one of many privately owned hotels in the French capital used as temporary shelters by social services.
Immigrants are often placed in hotels while they wait for housing
With Paris experiencing a shortage of accommodation, authorities are struggling to cope with the housing demands of its more destitute residents.
Cheap hotels like the Paris-Opera - home to several African immigrants - play an important role in filling this need, the authorities say.
There is no suggestion that the Paris-Opera was at fault, but the fire there has highlighted the housing problem facing many families.
According to critics, living conditions in some hotels used to house families are appalling and a thorough overhaul of the emergency housing system is needed.
Cheap hotels are part and parcel of Paris' Bohemian legend. Until the 1950s, they provided homes for generations of provincial migrants, unskilled workers and aspiring artists - described in vivid detail by former guests such as George Orwell and Ernest Hemingway.
But in recent decades, slum clearance and the advent of social housing have led to a sharp fall in the number of "hotel meubles".
According to one study, there were only 1,200 in 1989 and 660 in 2000.
However they have found new customers in recent years - social services.
"We have to find rooms for families in dire need," said a spokesman for the Paris city authorities.
"Especially when children are involved - we just can't let people live on the street."
But according to Jean-Francois Blet, a Paris councillor who has been lobbying for reform of the city's housing system, many of the hotels used for temporary housing are "shabby".
Mr Blet, who belongs to the Green party, says 100-150 of those remaining in Paris should be taken over by the authorities and turned into proper temporary housing centres. Only seven of them have been taken over so far, he said.
"The Paris municipality has agreed in principle to deal with the problem," he said. "But progress is slow."
Although most of the guests at the Paris-Opera were immigrants waiting to be re-housed, tourists were also staying at the one-star hotel, attracted by its central location and affordable rates.
Although the only fire exit was down the main staircase, this is not illegal in older buildings. Indeed, firefighters said the building was only inspected last month.
An investigation is under way.
But whatever the cause of Friday's fire turns out to be, the blaze has highlighted the adequacy of immigrants' living conditions.