Umm al-Rasas (also spelled Umm ar-Rasas and Um er-Rasas) is an important archaeological site. The site is especially known for its magnificent Byzantine mosaics, which have been uncovered in two churches dating from the 6th and 8th centuries.
Umm ar-Rasas contains ruins from the Roman, Byzantine, and early Muslim civilizations. The majority of the site has not been excavated. Among the portions excavated so far include a military camp, and several churches. For its unique blend of civilizations, Um er-Rasas was inscribed as a UNESCO World Heritage Site  in 2004. Its structures date from the 3rd to 9th centuries and most have not yet been excavated.
Actually, the term “Rassas” refers to the Arabic root “Rass” indicating the action of putting something on top of something else in perfect alignment. Therefore, Um er-Rasas or “Mourassas” in the top onomastic of the region is a term indicating a well-built structure The builders at Umm al-Rasas used a technique which involved fitting the rocks together closely, resulting in strong structures that have resisted several earthquakes. The arches still standing, as well as the Stylite tower itself, testify to the superior quality of construction. 54UmmrRasas08big