With three-plus days in Lima, we had quickly ticked off the 'musts' on our list and found ourselves looking for more to explore. Our concierge mentioned Pachacamac, ruins that were fairly recently discovered about an hour outside of Lima. We were intrigued.
We negotiated a day rate to explore with our driver and he took us out to the ruins where we hired a guide/historian to explain what we were seeing.
The ruins, which are still not completely unearthed due to funding issues, include a number of temples used by the Incas and pre-Incan civilizations dating back to 200 AD. If you're looking for a day trip that takes you outside of Lima, this is a good way to spend a half of a day. The guide is a must to have any understanding of what you're seeing. Plus, the drive from Lima's city center to Pachacamac, littered with shantytowns, is an eye-opening one.