#5 High House was used to heat treat massive forgings such as propeller and turbine shafts, and probably battleship cannon barrels. Even though BSC was primarily a steel mill, this was also a machine shop capable of almost any project.

One side of the building is a massive vertical gas furnace for heating the part. The other side is a huge tank, filled with oil, used for quenching the heated part. The low section contains hoisting machinery. You can just see the cable to the pulley at the top of the building that hoisted the parts. The furnace and tank actually extend into the ground. I think they could handle pieces about 100 feet long.

The interior ironwork supporting this brick building is just incredible :)

Later I'll post some interior pics, but everything is so massive it's hard to convey much.