time capsule

informal Something that captures the unique styles, sensibilities, trends, etc., of a certain time period. A reference to literal containers in which goods or information are stored as a historic cache for future generations. The play is essentially a time capsule of 1960s Rhode Island, right down to the slang, the hairstyles, and the songs playing on the jukebox. My parents' house is still a time capsule of our childhoods. I honestly don't think they've changed anything since I was 12 years old.