The district of Lienz incorporates the whole of East Tyrol and since the annexation of the present-day South Tyrol to Italy (1919) it is no longer directly connected to the rest of the province of Tyrol. The economic development of the region was hampered for a long period of time due to its peripheral position away from bigger centres and initial bad transport conditions. It was only the building of the Felber Tauern Tunnel in 1967 that made it possible for the region to catch up economically. International companies have opened branches in East Tyrol, among them Liebherr and Durst and Loacker. The central settlement and economic centre is the town of Lienz which is located in the basin of the same name at the confluence of the rivers Drau and Isel. The Romans already built their town Aguntum, whose ruins can still be seen near the present-day Dölsach. Further important communities are Matrei in Osttirol and Sillian. From the North Tyrolean point of view, the side valleys in this region are the most isolated parts of the province. The district of Lienz is part of the Nationalpark Hohe Tauern which includes the Großglockner, Austria's highest mountain, and the Großvendiger. This mountain chain is also the watershed for northwest to north streams and provides East Tyrol with generally milder weather than is the case for the rest of the province.