I’ve seen this before where someone has provided a nest for Great Horned Owls.
As Owls don’t do their own nest building and reply on other birds like Crows to do it for them.
Since Crows build a new nest each season…the old nest is there for the taking and will often be used by Great Horned Owls if in a suitable location.
These nests after being used in a second year are usually unusable again and a new location would be required.
Humans lend a helping hand by constructing nests for owls to use year after year…such is the case at this location.
Unclear just how long the nest has been there…but does appear to be very sturdy and should last a long time.