At ItalianSide, we have a big collection of old photos from almost every town in Toscana and in Italy (We have more than 90% of Italian towns in our pictures archives!).
We have several images of Viareggio too and here you can see one of them (click on the picture to enlarge).

If you are interested in historical maps, here you can see an old map (1800) of Viareggio and its area.

If you are interested in this or other pictures with no watermark of Viareggio just send an email to viareggio@italianside.com, with your request.