Even though the park grounds have several miles of hiking trails and a tour of the historic mansion, I instead decided to hang out along the Hudson River and observe the wildlife that passed through.
I also took photos of the surrounding scenery around the area, which included landmarks such as the Esopus Lighthouse, the Wilderstein Mansion and the Catskill Mountains. Make sure to bundle up this time of year!
Photos from Mills Mansion (click photos to enlarge)
Local Exploration 
The grounds of the mansion look very nice. I have been to Newport and a few of the mansions there. Thanks for enlightening me on another estate that may be worth visiting.
We have quite a few mansions and historic sites along the Hudson River, many of which have decent hiking trails on the grounds. I’ve also been to Newport, my personal favorite was The Breakers.