Building the Ultimate - Extreme Machines [Discovery-Science ch]
Megastructures [N Geo]*
Modern Marvels [history]
Voyages [History international] had a bunch of train centered episodes and I just love them all.
lol Anything about Disney world [Travel ch]
* Am I the only one here that likes that series? Because here it is rated like 6.5 or something. I can understand a few shows like the science of bricks would suck, but how can anyone not like Sears Tower or such episodes?