Battambang has a rich supply of colonial era architecture. As in Kampot, there are a lot of buildings from the late nineteenth and early twentieth century, in various states of decal or restoration. Some of the best examples are facing the river, between the old governor's mansion and the Art Deco Psar Nat market. Few of the buildings have been completely restored, but most are not beyond repair.
A stroll around town will take you a couple of hours, at most.