Port

[Brom]

No, you cannot age even Portos forever. '77s are drinking very well right now. However, as noted above, you could certainly hold this bottle for another decade or more.

A key question that must be answered in determining whether to drink or hold is "How has it been stored?"

You say you have "a bottle". Have you had it for 23 years and kept it in proper storage conditions? if not, where was it? The best ports can go bad in 10 years if poorly stored.