The tower of San Giovanni in Campo on the island of Elba (Italy), is a very interesting example of Pisan military architecture of the 11th century. Through analysis of technological finds in the seriously deteriorated structure, it was possible to reconstruct both the original structural elements and the wooden parts of the tower. The construction technique goes back to classical Mediaeval methods. The paper is a result of research, documentation and cataloguing work carried out by the research unit Ancient structural technologies on the minor monumental heritage. A reconstruction of the monuments is also illustrated.