Wallsee-Sindelburg, Lower Austria, market town in the district of Amstetten, alt. 275 m, pop. 2,109, area 25.93 km2, on the south bank of the River Danube, north-west of Amstetten. - Wallsee-Mitterkirchen run-of-river power station (built 1968, 210 MW; administration office in Wallsee, the power station itself is located in the municipality of Mitterkirchen im Machland, Upper Austria) with river and lock control office, watersports centre; horticultural business, transport business with gravel works, summer tourism. - Auxiliary troop camp in Roman times (probably the antique Adiuvense); market within the rectangular base of the former Roman camp; castle, developed from a medieval fortress (1364), with tower (85 m), underwent several alterations and extension in the 19th century, in prominent location above the River Danube, Roman museum; subsidiary church of St. Anne (mid-18th century); column dedicated to the Virgin Mary (1710); parish church in Sindelburg (first documented mention 1138), late-Gothic hall church (1504) with Baroque alterations and numerous figural sepulchral monuments decorated with coats of arms (15th /16th centuries).