Converting the old London Hospital back into use as the new Town Hall and Tower Hamlets civic centre has begun after dangerous asbestos was removed.
The prestigious Whitechapel site is to be more open to the public than the council's isolated Mulberry Place tower in Blackwall that the mayor admits is "forbidding".
But the £100million project has been hit with problems of asbestos.
"It had loads of asbestos, more than we anticipated," Mayor John Biggs has told the East London Advertiser. "The asbestos was a considerable problem to get removed.
"Asbestos seemed to have been used everywhere when they rebuilt the London hospital down the years."
Now the asbestos used in times past for fire-proofing has been carefully taken out from the building which has been empty since the Royal London moved in 2012 to its new tower complex at the back.
"Whitechapel is going to be the hub of our community," the mayor added. "The town hall will have public access, not like our current building which is a bit forbidding being stuck out miles away in Blackwall.
"A previous administration in the 1980s deliberately selected the middle of nowhere because it wanted to break up Tower Hamlets into seven little 'mini boroughs' which didn't work."
The new town hall puts council services like housing and health under one roof.
It is to have a café, public library, free wi-fi, meeting rooms and community spaces.
The mayor was on a fact-finding tour with some of his top staff looking round the complex to see where his offices will be when the project is complete in 2022.
For now, it was hard hats, safety visors and boots, treading carefully on precarious floorboards pitted with holes.
This massive building site stripped of all plaster and asbestos has walls now exposing ancient brickwork, some in place from Georgian times when the London Infirmary first moved out from the City to the green fields of Whitechapel in 1752.
The mayor was anxious to leave his mark in this historic site with a time capsule to be opened by future generations.
The small metal cylinder with a letter from the mayor and letters from schoolchildren was sealed up in brickwork next to an old fire place. It contains a £5 note, a £1 coin, a picture of council members and "a bunch of photos" that the mayor included showing the original hospital.
The town hall is timed to open in 2022 opposite Whitechapel station and Crossrail's transport hub with its direct 40-minute link to Heathrow.
It will be run by up to 3,000 staff with day-today functions headed by council chief executive Will Tuckley who toured the site with the mayor.
He said: "Whitechapel is the heart of the community where the council should be.
"This will be the nerve-centre of the council — there's nowhere better connected than Whitechapel."
The old hospital comes with a pedigree of history with historic figures like Edith Cavell, who trained to be a nurse before she opened her medical mission in Belgium where she was later executed by firing squad by the German Occupation forces in 1915 for helping Allied soldiers escape during the First World War.
The hospital was also where a severely deformed Joseph Merrick, known as the Elephant Man, was allowed to live out his life in the 1880s after being rescued from a freak circus by surgeon Frederick Treves. Merrick died in 1890 from what medical experts today believe may have been Proteus syndrome, though inconclusive.
Cavell and Merrick are part of the story of this magnificent listed building with its distinctive Greek pillars and grand entrance preserved as the main facia on the Whitechapel Road, its Georgian terraced rear incorporated into an atrium linked to a new extension at the back.
The scheme is part of the masterplan Whitechapel regeneration including a £300m life sciences campus, seven public spaces, 3,500 new homes and 5,000 jobs. It brings together council services which will free up former office sites that can be used for 700 more homes with a third at low-cost.
The authority couldn't have hoped for a better location for its town hall when it acquired the old hospital for a "bargain basement" price of £9m in 2015 from the NHS. It will soon be, after all, just 40 minutes from Heathrow.
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