Planet Walk.

Journalist Larry Kales wrote in with this link to a great Sagan-Blog-a-Thon post featuring Dr. Sagan's Planet Walk in Ithaca.

The entry was posted by Stephen Frug and appears on his blog, Attempts. Aside from a detailed description and excellent photographs, Frug also links to the podcast audio tour, written by Sagan, and voiced by Bill Nye. Now you can participate from anywhere!