<p>This fourth volume (Proceedings 4) presents the results of an international conference held at the Museo de los Or&iacute;genes (Casa de San Isidro) in December 2008. The work is divided into three parts: Four studies on general aspects of the &#39;rock world&#39; in the Iberian Peninsula, the chronology of the caves artificially created, the &#39;troglodyte&#39; in the Greco-Roman tradition, and the chronology of rock-cut tombs. The second part looks at eleven studies of various regions and &#39;rock complexes&#39; in the Iberian Peninsula (&#39;San V&iacute;tor&#39;, in San Lorenzo da Barxacova, Parada del Sil, Ourense; &#39;El Bierzo&#39;; the upper valley of the Ebro; &#39;San Mart&iacute;n de Albelda&#39;, in &#39;La Rioja&#39;; the middle valley of the Cidacos river; the high valley of the Arlanza river; &#39;San Frutos del Durat&oacute;n&#39;, Segovia; the suburbium and territory of Ercavica in Late Antiquity and Early Middle Ages; the territory of Sierra Magina; and finally, the Almagruz caves, in Purullena, Granada. The third part examines parallels in other Mediterranean regions, such as the &#39;rock city&#39; of Matera (Italy), the valley of the Euphrates (northern Syria); the churches built on the rock of Lalibela (Ethiopia), and the &#39;rock world&#39; in the provinces of &#39;Arabia&#39; and Palestina Tertia in Jordan.</p>