Ubi sunt is a poetic motif built around the question "Where are they now?" It usually looks back on lost people, places, pleasures, or eras and asks what has become of them. Poets use it to express grief, nostalgia, and the briefness of human life. The phrase appears often in medieval and early English poetry, especially in laments and meditations on mortality.
Example
Where are the bright hats of summer,
where the laughter that filled the lane?
Only the wind in the hedges
answers my question again.