There are no photos of the interior of Himeji Castle for a reason. I didn't get in. On the way to Himeji from Ibaraki, I stopped by the Panasonic Center in Osaka which was a mistake. Similar to the Samsung Experience in the Time Warner Center, the Panasonic Center is a showcase of everything the brand (and it's sister brands) has to offer. It actually one-ups all the other brand experience showrooms I've seen because it goes in depth describing the technology employed in its various products, including demos, cut-away and exploded physical models and videos describing not only the products, but the company and factories. The ladies manning the showroom also took their jobs very seriously, trying to explain the product or technology to me everytime I approached a product for a closer look. Since there is a much larger one in Odaiba, Tokyo, I'll expand on this after taking Terry there.
As you can tell, I was thrilled to be in the Panasonic Center and ended up spending way too much time there. By the time I got to the town of Himeji, I had less than five minutes to make it into the castle before the doors closed. It took me around eight minutes to walk briskly / jog from the JR Station to the Castle doors. I swear if there were no crossing guards, I would've ran through every red pedestrian light.
I took photos of what I could on the exterior and milled around the large park at the center of the castle grounds. It's always interesting to imagine how an attacking army would break down a castle's defense and Himeji looked impenetrable. Since I didn't have a chance to do any in depth reading about Japanese Castles before arriving, I was only able to compare it to Nijo-Jo in Kyoto. The defenses looked a lot more interesting on these castle walls than Nijo-Jo; the battlements had what I thought at the time crazy looking gunports or teppôsama (but for good reason, the large opening on the outside of the wall allowed for a wide range of attack angles while protecting the shooter). This was also the first time I saw ishi-otoshi mados (see the first photo).
If Japanese castle architecture interests you, read this excellent essay by a Kenyon student, and there's always Wiki.