On an early fall day, with just a hint of red tinting the maples, the view from the summit of Deasey Mountain is spectacular.

To the west stand the rugged, treeless basins and knife-edge spine of Mount Katahdin. Off to the south, you see Wassataquoik Valley in the near distance, the peaks of the 100 Mile Wilderness beyond. To the east and north, more wild Maine woods and hills rolling for miles, to the Canadian border.

It’s a fascinating view, partly because until recently, this mountain and most of the foreground were owned by one person. In August, the entrepreneur Roxanne Quimby donated it to the federal government, and President Obama designated the area the Katahdin Woods and Waters National Monument.

Now the 87,500-acre monument — adjacent to Baxter State Park — is Maine’s largest parcel of federal land, nearly twice the size of Acadia National Park, and I’ve come to explore.