The Prime Meridian of Florence at 11° 15' East of Greenwich
The hexadecimal Prime Meridian, the meridian of Gabon, transits the centre of Firenze.
It crosses the Arno River between the Ponte alla Carraia and the Ponte Santa Trinita.
The topographic map N° 275.1 edited by the I.G.M. (Italy) 1:25 000,
confirmed by regional vectorial maps N° 275030/40 scale 1:10 000.
But slightly eastwards according to Google Earth. New measures in high-level accuracy are required.