At what point is the Delaware Block House[1] still the original building[2]? You can see the roof was replaced recently, and presumably the rendering[3]..

[1]: Delaware, the Block House https://en.wikipedia.org/wiki/Block_House

[2]: https://en.wikipedia.org/wiki/Ship_of_Theseus

[3]: In the episode "Heroes and Villains" (Only Fools and Horses UK Sitcom), Trigger wins an award for having owned the same broom for 20 years. He reveals that it has had 17 new heads and 14 new handles, but insists it is still the same broom.