The towered city is considered a unique jewel of the medieval architecture and town-planning in Italy. It was for this reasons that it was placed on the UNESCO World Heritage Sites List back in 1990. The ancient township, erected on a natural highland, appears today nested within high defensive walls, and a distinguishing place thanks to the numerous towers which make the medieval town's skyline completely unique. As a matter of fact, San Gimignano gets credit for having been able to maintain these typical medieval elements – the high defensive towers erected by aristocratic families – untouched over the centuries. This is a great fortune for Sangimignano, as many other italian cities got their walls destroyed or replaced by more recent constructions throughout the centuries.