Nurhag, a prehistoric monument peculiar to Sardinia, where some thousands occur. They are round towers, of one, two, or three storeys, with sloping sides, the height being generally equal to the width of the base. A staircase leads to a platform on the top. Nothing is known of their origin or purpose. The talyots of Majorca and Minorca bear some external resemblance to these towers; but it is not known whether they possess a staircase, and there is always a table formed of an upright flat stone, with a similar stone crossing it.