Leaside is a neighbourhood in Toronto, Ontario, Canada. It is located northeast of Downtown Toronto, in the vicinity of Eglinton Avenue East and Bayview Avenue. It is one of the most expensive and exclusive neighbourhoods in the city. The area takes its name from William Lea and the Lea family, who settled there in the early years of the 19th centur…Leaside is a neighbourhood in Toronto, Ontario, Canada. It is located northeast of Downtown Toronto, in the vicinity of Eglinton Avenue East and Bayview Avenue. It is one of the most expensive and exclusive neighbourhoods in the city. The area takes its name from William Lea and the Lea family, who settled there in the early years of the 19th century. The area first developed as farmland along with Toronto through the 19th century. It was incorporated as a town in 1913. In 1967, it amalgamated with the township of East York to form the borough of East York. In 1998, it became part of the city of Toronto.