One of the few surviving dolmens of Lampedusa withg a huge 3x3 meters capstone, two stone pillars and a tomb chamber below the capstone.

Dolmen of Lampedusa 

Notice how the capstone is supported by two small stone pillars next to the main entrance:

Pillar Detail

Chamber Detail

Interestingly a similar Dolmen structure has been found in Malta: 

Dolmens of Malta and Gozo
Credit: Daniel Cilia 
Courtesy of D.H. Trump from "Malta Prehistory and Temples"

A video of the Dolmen from Lampedusa: