London Galleria is interesting. The Central Library (which is quite nice) is the old Bay Store, closed soon after the Eaton's closed in 1997 or 1998. The Eaton's is now the Rainbow Cinemas. Much of the mall was given over to office and institutional use and is therefore useful, yet not in its original purpose. Interestingly, Galleria is a po-mo expansion of the old Eaton Galleria, a smaller indoor mall built in the early 1960s that had one of the four blocks.
Part of the problem is that downtown malls in smaller cities hardly worked, especially in places like London where suburban malls, with ample, free parking were more attractive to a suburbanized population. Sarnia, Guelph, Kitchener, Peterborough, Brantford all learned that lesson the hard way. London was especially over-malled. Eaton's collapse (partly brought about by its downtown mall projects, supported by the province, which were total failures) caused these marginal malls to empty quick. Many had cinemas as well, a good idea until the big-boxed megaplexes took over, all in the suburbs.
If that's your kind of thing, Hamilton's Jackson Square/Hamilton City Centre is the place to be. The wholesale clearance of six blocks of downtown Hamilton, and the replacement with a giant, indoor shopping mall was to be the saviour. Instead, it is a dank relic of early 1970s mall architecture, though the food court was renovated; the mall has some life to it compared to many of its contemporaries.
The old Eaton store, adjacent to Jackson Square was demolished and replaced by a pomo mall separate from Jackson Square but linked to it. The Eaton's became a Liquidation World and much of the mall became city offices.
Guelph pretty much got rid of its mini-Eaton Centre, but Kitchener, Sarnia, Brantford and Peterborough still have them.
