Paris, France
From Geohashing
The graticule in Paris has been calculated from "Notre Dame de Paris", considered the heart of the city. There's a stone saying that there (it is even said to be the center of all roads in France, "Point 0 des routes de France"), so it must be true.
The area around Paris is full of Parcs, small towns and farms to meet up.
The gps location for 2008-05-20 is in a farm at Moissy-Cramayel.
To get to the location, use [Parisian Common Transport website].