Fascinating tour! Friends of Pump House - a nonprofit organization periodically offers tours. The tours are first come, first serve. There is a suggested $10 donation which I happily paid. The tour is about 30 minutes. Hard hats were provided as they are required. There are some uneven walking surfaces and you take stairs to get to the upper area. Our guide provided lots of info on the history and answered questions. There’s plenty of shaded street parking and also a nearby parking lot.