You're thinking of the Vikingsholm Castle in Emerald Bay, Lake Tahoe. That was my first thought too, but I don't think it's the same place. I pinged someone that probably knows.
Thanks Big Meanie. That one is lovely, but that wasn't the one I was thinking of when I posed the question. Although, the trees are similar. : )
What made me think Lake Tahoe is those massive rocks on the shoreline....many of the beaches at Tahoe are actually man made where the rocks were removed and the sand was hauled in.