1970’s Ringworld is the first volume in Larry Niven’s Ringworld series, which is set in Niven’s Known Space universe.
Louis Wu’s teleport-booth-tour of an inexplicably backward-spinning 29th century Earth1 is interrupted when the ancient man is waylaid by Nessus, a Pierson’s Puppeteer. This is an unexpected development, not least because the Puppeteers have not been seen on Earth since they fled Known Space in the 27th century.
Nessus is determined to hire Louis. The alien has just the right currency with which to purchase the ancient human’s time: a precious commodity that the bland, homogenized world that is Earth of 2850 cannot offer Wu: novelty.
Mind you, the chance to flee a doomed galaxy does not hurt.