Normally, aircrafts remain airworthy for around 22-25 years before they are written-off!
I came across one such great piece—a Boeing 737 while traveling to Jaipur.
It seems that the owner bought it as a scrap and parked it next to his Dhaba (a road side eatery) where travellers can have a glimpse of it while on the way.
I stopped by and insoected it throughly to have a feel about whay materials are being used and the overall structure that is used while manufacturing an aircraft!
Aircraft building is, without doubt, an impressive example of technology in use!