This lighthouse is owned by the US Coast Guard.
The grounds are open, but not the tower. That being said, it's a bit tricky to get to, since there are no signs.
We finally found it on our second trip, going down the road for the Castle Hill Inn, which looks private, but is not. You'll park at the marina, just before you get to the inn.
I found the lighthouse using the link from Lighthouse Friends: http://www.lighthousefriends.com/light.asp?ID=396
Narragansett Bay dominates the geography of the tiny state of Rhode Island, extending 25 miles northwards and inland from the Atlantic Ocean right into the heart of its major cities. It is fed by the watersheds of 3 major rivers: the Blackstone, the Taunton and the Pawtuxet. Narragansett Bay defines the region's culture, its history, sense of place and quality of life. The cities of Providence, Newport, Fall River, Warwick and Newport all owe their start to the bay and the opportunities it provided for water power, commercial growth and transportation. Once badly polluted, the Narragansett Bay has made a tremendous comeback in the last 3 decades as communities all around the bay have revitalized their connection to the bay and taken steps to curb human impact. Aerial Vr plans a series of panoramas intended to capture the area's unique natural beauty, both from its surface and from the air as well as the vitality and uniqueness of its communities.