"Did they look realistic? "
You are asking the guy who in all seriousness suggested using buildings made of Legos!
From a distance they looked as good as many of the commercially available O scale pre-assembled buildings look out of the box. There are size differences, such as roughly 12 foot ceilings rather than 8. Close up they betray their origin, but I suspect most modelers would have little difficulty masking this.
@PJB-If you saw some of these buildings you might agree they can be made similar to the types of buildings you are talking about. What they are not though is models of the buildings you are talking about. Here's a link: https://www.flickr.com/photos/decojim/923765365
