Posting one of the shortest but my favourite descriptions here. I enjoy it because it describes so succinctly and avidly the sweet regret of wanderlust, of meeting a city that one dreams of in his youth only to find that one is no longer young, and desires fade into memory:
"When a man rides a long time through wild regions he feels the desire for a city. Finally he comes to Isidora, a city where the buildings have spiral staircases encrusted with spiral seashells, where perfect telescopes and violins are made, where the foreigner hesitating between two women always encounters a third, where cockfights degenerate into bloody brawls among the bettors. He was thinking of all these things when he desired a city. Isidora, therefore, is the city of his dreams: with one difference. The dreamed-of city contained him as a young man; he arrives in Isidora at his old age. In the square there is the wall where the old men sit and watch the young go by; he is seated in a row with them. Desires are already memories. "