Nuraghe Appiu archaeological park is surrounded by a suggestive and uncontaminated environment. It was probably born as anuraghe with only one tower, to which, later, other towers have been united, connected among them by corridors, outlining a quadrilobate figure.
In its simple form the nuraghe is a flat-topped conical tower built with stones of varying size laid without grout (dry walls). The masonry consists of courses of stone laid in more or less orderly fashion. In many cases the stones were laid as they were, but more often they were dressed to facilitate their laying. In the upper part of the towers, the part most exposed, the stones are usually dressed with care to ensure a perfect fit between the different elements and thus improve stability.
References:Střekov Castle (Schreckenstein) is perched atop a cliff above the River Elbe, near the city of Ústà nad Labem. It was built in 1316 for John of Luxembourg, the father of the Holy Roman Emperor Charles IV, to guard an important trade route to Germany. After changing hands several times, the castle was acquired by the Lobkowicz family in 1563. Its strategic importance led to occupations by Imperial Habsburg, Saxon, and Swedish forces during the Thirty Years' War, as well as successive sieges by Austrian and Prussian armies during the Seven Years' War.
Although Střekov Castle was heavily damaged during those conflicts and abandoned as a military installation by the end of the 18th century, the 1800s saw many poets and artists visiting the castle, drawn by a new trend of interest in romantic ruins.