This building has a long and diverse history. It was built in 1884 on the southwest corner of Dundas and Rectory as London East Town Hall. It didn't remain a town hall for very long though; London East was annexed by the city the following year.
Strangely for London, the fact that the building could no longer be used for its original purpose didn't result in it being torn down. A crowning example of adaptive reuse, over the years the hall has been used as a fire station and a Public Library branch among other things. For many years now it's been a performance hall, providing an excellent venue for a variety of musical events. An especially memorable concert was Scott St. John's appearance in December 1997, headlining a group of London chamber musicians paying a tribute to Franz Schubert.
Some might say supplying a new roof for a heritage building shouldn't be part of City Hall's mandate. But when it's not just heritage at stake, but also the performing arts, London really needs to cough up the cash. The "east end" has been looking after its "town hall" for a good long time and the city needs to continue the trend.