 The entrance to the Siq contains a huge dam, reconstructed in 1963 and again in 1991, designed to bar the mouth of the Siq and reroute the waters of Wadi Musa.The dam is a fairly true reconstruction of what the Nabataeans did to control Wadi Musa between the 1st century BC and the beginning of the 1st century AD.The entrance also contains the remnants of a monumental arch, of which only the two abutments and some hewn stones of the arch itself have survived.