The Catherinenberg ruins are ruins of a 18th-century sugar and rum factory. The consist of a circular horse mill and a very well preserved wind mill. They were part of the Hammer Plantation and are one of the oldest plantations on St. John
Looking up to the sky through the round hole is amazing, you might even want to go there at night, lay on your back and watch the stars.
Aside from the ruins you are also very likely to encounter deer and it also is a really nice area to go for a run.
How to get to Catherinenberg Ruins:
From Cruz Bay take Centerline road towards Coral Bay (that is the road that starts at roundabout and goes past Dolphin Market), Follow the road for a little over 4 miles until you see a big brown National Park sign to the left and make a left there (it says St. John Head Road).