Linking the Gondar and Gojam Regions of Northern Ethiopia is the Portuguese bridge, built by emperor Susenyos, from volcanic rock bedded on lime mortar, either at the at the end of the 16th or early in the 17th century. It spans the Blue Nile, a short distance after the Blue Nile plunges 45 metres, to form a spectacular waterfall called Tis Isat (Water that Smokes) or the Blue Nile Falls.