When is something considered old? In fashion it might be three months. When it comes to cars and trucks, it could be 10 years.
A home might be considered old when it has been around for 50-60 years. A person might be considered old at age 70 or 80.
Buildings in Canada could be considered old from age 40 to age 125. By our standards, much of historic Germany, Austria, and Hungary must be ancient.
After travelling for two weeks up the Rhine and then down the Danube, I gained a new appreciation for the age of buildings.