Here is a picture of an unidentified ammonite fossil. It was found embedded in a step at the Piazza San Marco in Venice, Italy. My guess is this might be limestone from the region around Verona Italy. That area is known for its ammonite fossils found in building materials. According to this flickr web page, there are paving stones quarried in the Alps known as "Ammonitic Red" or "Nodular Limestone of Verona" from the Jurassic Period (see https://www.flickr.com/photos/greenriver/357717233/). The ammonite fossil I came across was documented in 2012 in this blog along with some more ammonite fossils found Venice: http://ytaba36.wordpress.com/2012/03/08/ammonites/
The step is in front of a coin and stamp shop called Degani S.A.S. di Montanari G. & C. (S. Marco 79, 30124 Venezia).
In a related note, they had some dinosaur and reptile stamps for sale in the display window. More about these in a future blog post.
Here is a picture of San Marco Square in Venice Italy.
Learn more about ammonite fossils in Italy:
Fossil Museum in Bolca: http://www.tourism.verona.it/en/enjoy-verona/art-and-culture/monuments-and-sights/fossils-museum-in-bolca
Fossil Museum in Bolca: http://www.veronissima.com/sito_inglese/html/tour-museums-natural-history.html
Quarry in Verona: http://ramkitten.squidoo.com/ammonitic-limestone-verona-italy