99 years or 999 years. AKA a leasehold
If I have a 999 year leasehold, that's the same as ownership in practical terms as my ownership goes away when the government fails and is replaced/taken over/overthrown.
In tech specifically, a 99 year lease is practically permanent as well. (1925 was before the first RF transmission of a television picture.)
* Maybe Japan is an exception here.
They're claiming none of their governements is over 999 years old.
Denmark's constitution is from 1849 [1].
Hungary's constitution is from 1949 / 1989 [2].
China's government is form 1949 (when the previous government got overthrown and went to Taiwan) [3].
I'm not going through the whole list.
[1]: https://en.wikipedia.org/wiki/Denmark#Government_and_politic...