Sibiu (German Hermannstadt , Hungarian Nagyszeben in Latin Cibinium ) is the county seat and largest city of Sibiu county , Romania . Sibiu is an important cultural and economic center of southern Transylvania. Sibiu Lutheran Cathedral (German Evangelische Stadtpfarrkirche ) is one of the most beautiful and impressive Gothic buildings in Transylvania. The Evangelical Church Cathedral C.A. and parochial church of the parish community of Sibiu having the largest community of faithful Lutheran Romania