The Mason House on Analoston Island
Here is a great contribution from GoDCer Mike.
We were always told that this island was donated to the Roosevelt Society back in the day but I found documents that it was sold for $20,000 that is a fine sum. On another note I always walk my dogs off leash here and whenever I am told by park rangers I have to obey the law I have stated that I do not have to as we once owned it and are exempt. Has worked every time.
We called it Anna Lawson Island … still do.