widely spoken and mutually understandable of the Semitic languages (the language group containing many of the languages spoken through the empire), Aramaic grew in importance throughout the Neo-Assyrian period and increasingly replaced the Neo-Assyrian language even within the Assyrian heartland itself. From the 9th century BC onward, Aramaic became the de facto lingua franca of the Neo-Assyrian Empire, with Neo-Assyrian and other forms of Akkadian becoming relegated to a language of the political elite. From the time of Shalmaneser III, in the 9th century BC, Aramaic was used in state-related contexts alongside Akkadian and by the time of Tiglath-Pileser III, the kings employed both Akkadian and Aramaic-language royal scribes, confirming the rise of Aramaic to a position of an official language used by the imperial administration. During the time after the fall of the Neo-Assyrian Empire, the old Assyrian language was completely abandoned in Mesopotamia in favor of Aramaic. By 500 BC, Akkadian was probably no longer a spoken language. Modern Assyrian people refer to their language as "Assyrian" (Sūrayt or Sūreth). Though it has little in common with the Assyrian dialect of the Akkadian language, it is a modern version of the ancient Mesopotamian Aramaic. The language retains some influence of ancient Akkadian, particularly in the form of loanwords. Modern Assyrian varieties of Aramaic are often referred to by scholars as Neo-Aramaic or Neo-Syriac. As a liturgical language, many Assyrians also speak Syriac, a codified version of classical Aramaic as spoken at Edessa during the Christianization of Assyria. Another language sometimes used in ancient Assyria as a language of scholarship and culture, though only in written form, was the ancient Sumerian language. At the height of the Neo-Assyrian Empire, various other local languages were also spoken within the imperial borders, though none achieved the same level of official recognition as Aramaic. Architecture There are three surviving forms of primary evidence for the architecture of ancient Assyria. The most important form is the surviving buildings themselves, found through archaeological excavations, but important evidence can also be gathered from both contemporary documentation, such as letters and administrative documents that describe buildings that might not have been preserved, as well as documentation by later kings concerning the building works of previous kings. Assyrian buildings and construction works were almost always constructed out of mudbrick. Limestone was also used, though primarily only in works such as aqueducts and river walls, exposed to running