There are two ways a building can be timeless:-
1. Affected by the content and the context through time but is able to respond to them well
2. Unaffected by the content and the context through time
Gothic architecture is the second type of timeless architecture where its construction (and ornamentation) is said to be done well.
And its beauty in turns, appreciated by many in so many years although its formal effect does nothing like modern architecture (significant effect affected by content).
In other words, it is the same old piece of architecture no matter what period of time that you are looking at it, and the function (content) within does not makes it any less distracted from its beauty.