Engines of our Ingenuity
This site is amazing. The site is the text version of a radio show produced for the University of Houston. I listen to NPR on the way to work in the morning. This show plays on that same station later in the morning. I miss it every day. I cannot receive radio in my dungeon.  I use internet radio to take up the slack. I suppose they have to pump sunshine to me as well.
Engineers will love this style, because it is straight forward fact on top of interesting presentation. The site has one advantage over the radio show. The site has pictures and diagrams.
Here are some I like.
No.10: The Medieval West
No.16: Homo Technologicus
No.18: Poets View the Ind. Rev.
No.35: The Influence of War