The Lepini people

I took this picture on the grounds of the Fossanova Abbey, which is in Sonnino scalo. I've been seeing these signs around the Sonnino area for the past few years. I asked my cousins about about the structure on the sign.

The area around Sonnino is called the "Lepini Plain". The Lipini are the ancient people of the Sonnino area. This structure is a rendering of what their dwellings looked like. My cousins also mentioned that in the hills right behind Sonnino there are still ruins of ancient Lepini homes. Has anybody seen them?