Artist Melinda Hackett did just that - by erecting a round, cedar treehouse for her girls in their Greenwich Village backyard.
A neighbor reported her to authorities.
It took a half year of legal battles, but Hackett triumphed. Her Village treehouse could not only stay - it's been granted landmark status.
Hackett's actual home is from the 1860s and the treehouse has a permit - as recreation equipment that's allowed in the historic district.
It's apparently unique in one of America's most densely populated areas.
The townhouse once belonged to musician David Byrne of the Talking Heads.