I made a few trips there.... its fun. Go very early on not-so-busy days. You will be working long exposures most of the time.... its dark. Sometimes the most interesting places are almost pitch dark.
What I used most of the time.
* Heavy tripod
* 24mm, 50mm focal lengths.
* Flashlight w/ some gels to put in front. Used to "paint" in dark areas.
* Remote release
* Second camera with 90mm macro. Lots of small interesting things to shoot.
* Knee pads (I shot low most of the time)
* Old cloths (its an old dusty place). Its not heated either. So dress warm if cold season.
* If you are sensitive to dust, maybe a painters mask.
Just a taste of what you can see...
8 second exposure, 24mm, using flash to "fill" in the dark areas.
One of the unrestored areas deemed "sustained state of ruin".
8 second exposure, 24mm, flash light again
There is a nice cafe across the street from the main entrance. Good sandwiches cold and hot w/ soups. I recommend walking across, order to go, and take it back to the prison area to eat. I ate alone... it was an eerie experience to soak in... it was quick and fast to spend more time shooting before the tourists arrived. One of the photographers I was with decided to skip eating because she didn't want to stop.
Its huge..... a photographer can spend a couple days there to explore and shoot. Al Capones' cell is probably the most famous of the areas. You can only shoot through a small window. I recommend not waiting (spending time) to see that exhibit. All the shots people take all look the same... just look and move on to more interesting things. The other famous area is the barber's chair. Again... I took a few shots just like everyone else but I found other areas far more interesting. I also recommend putting the camera away (if you have time) and taking one of either the tours or self guided pre-recorded tools. This place has a huge historical value to modern buildings and our US history..... its a good learning experience. First wagon wheel designed building with mirrors to make it easy to monitor (pre-dates modern security camera). One of the earliest buildings with electrical, plumbing, and sewer. How the building and structure changed along with how we viewed crime and treated those that committed (From ol' Penitence days to the days of lockup).
Have fun!