Halifax has had a bunch, though nothing was as dominant as the Eaton's or Bay locations in Western Canada. The brick building in the middle of this photo used to be the downtown Eaton's (photos are mine):
The stone building on the far corner was Zeller's:
This one's obscure. It was a two storey store on Gottingen Street called "The People's Store". I've read that it was a department store but I don't know much about it:
Mills Brothers on Spring Garden Road has been in business since 1919 or so:
One early suburban store was the Chebucto Road Simpson's, built around 1920 or so at the end of one of the streetcar lines. This store was open as the Sears discount outlet until about 10 years ago, when it was renovated into office space in a somewhat unfortunate way:
There are some older mall ones from the 1950's and 60's similar to the ones pictured above. They're nothing special architecturally.