Fetching details from the dictionary...
reminiscence; nostalgia; thinking fondly of the past; recalling the old days
古都を訪ねて懐古の情に浸った。
I visited the ancient capital and immersed myself in nostalgia.
懐古趣味とは過去を慕う心のことだ。
Nostalgia means a heart that longs for the past.
老将は懐古の念に駆られて語り始めた。
The old general, driven by nostalgia, began to speak.