<prompt> Translate the following text to EnglishWataalamu wa vitu vya kale wamegundua kwamba kuna majengo 7,000 ya aina hiyo ya nuraghi katika kisiwa hicho, na wengi wao ni minara ya mviringo iliyojengwa kwa umbo la mviringo.  <response>: Archaeologists have located some 7,000 of these nuraghi structures around the island, most of them flattened cone towers believed to be parts of fortified citadels. 