Still extant? Do you have examples? The oldest Buddhist temples seem to be a few centuries older than it, but there's little reason to think that there's any organisational continuity there.

(Of course, if you want to get super-vague, one could semi-reasonably argue that the Catholic Church is just a successor state to the Roman Republic via the Empire anyway, which pushes it back to about 500BCE.)

Just curious, what did you have in mind? I cannot think of any extant religious institution with the kind of centralized singular organizational structure that the RCC has. Many “religions” (using quotes here because the concept of a religion is a bit of a complicated topic) are older than Catholicism but are or were more decentralized - like Hinduism.