Okay, so one of the things that crops up in fantasy more and more these days is incredibly huge structures. In the ancient world large structures were so costly to build that few got to be very big. And some of those led to serious problems for the builders. Modern fantasy, particularly in video games, has a tendency to constantly push boundaries in order to wow the viewer. This includes massive structures which even the modern world would struggle to construct.
Even so, for the new campaign world which I'm working on (albeit at a somewhat glacial pace) I do want to have some really huge structures and statutes here and there. Most will be left over from ancient times. I roughly want to have an age when dragons ruled, an age where giants/cyclops/titans ruled, and an age where huge demons and angels ruled. All of those ruling races would have to build big due to their larger-than-human size and all would have magic to make construction easier.
Then, a while back, I came across a page on the Wikipedia which is a List of statues by height (http://en.wikipedia.org/wiki/List_of_statues_by_height). Now, I think this is a very cool page in its own right, but it's a great resource for a DM's imagination. Check them out. One thing which jumped out at me is that the great majority of the largest ones (40+ meters in height) are Buddhist, in either China or Japan. BTW, most of the Chinese ones are modern, post-Communist constructions. These spectacular works of art are perfect inspiration for a GM to include monumental statuary in a game.