Sieghartskirchen, Lower Austria, market town in the district of Tulln, alt. 205 m, pop. 5,812, area 61.59 km2, between the northern edge of the Vienna Woods and Tullnerfeld Plain. - Office building of the Lower Austrian environmental protection agency; butchery and meat trade, wood processing. - Gothic parish church with Romanesque tower (second half of the 13th century), altered and furnished in Baroque style around 1740, large high altar, Johann Nepomuk column (1726); column of St. Florian (first half of the 18th century); parish church of Ried am Riederberg (1824) with Classicist high altar and pulpit, ruin of a Franciscan monastery, founded in 1456, burnt down in 1506, destroyed in 1529.