From the WHC Inscription:
The area covers some 15 km along the extreme eastern end of the Ligurian coast, between Levanto and La Spezia. It is a very jagged, steep coastline, which the work of man over the millennia has transformed into an intensively terraced landscape so as to be able to wrest from nature a few hectares of land suitable for agriculture, such as growing vines and olive trees.
The human communities have adapted themselves to this seemingly rough and inhospitable nature by building compact settlements directly on the rock, with winding streets. The general use of natural stone for rooting gives these settlements a characteristic appearance. They are generally grouped round religious buildings or medieval castles.
Read More at http://whc.unesco.org/en/list/826