A reconstructed red-brick palace on the site of the building where Shivaji spent his childhood from 1630. The original was destroyed in fighting between Maratha and Mughal forces; what stands today, opposite Shaniwar Wada, dates from the 1980s and houses dioramas, paintings, and tableaus depicting episodes from Shivaji's life.
The interest is historical rather than architectural -- this is a memorial more than a monument -- but for anyone trying to understand the local cult of Shivaji it is worth half an hour. The Kasba Ganapati temple, said to be the oldest in Pune, is right next door; combine them in one stop.