Schloss Weinberg, Medieval château in canton St. Gallen, Switzerland

Schloss Weinberg is a former manor house converted into a castle in the 1980s, located west of St. Margrethen above Lake Constance at 546 m. The main building measures about 28 by 11 m, with walls up to 1.5 m thick, two storeys on a high basement, and eight axes on the courtyard side. A four-storey corner tower and a stair tower flank a terrace reached by a twelve-step outdoor staircase; long outbuildings enclose the courtyard.

The estate is recorded in the Appenzeller Urkundenbuch under 9 February 1470. It long belonged to a branch of the lords of Salis from Seewis in Prättigau. In 1716 Albert Dietegen von Salis freed the property from the annual court tax and the 'Ewiger Verspruch' owed to St. Margrethen for 400 gulden; it was then leased and finally sold, passing through several owners. Rudolf Kessler bought the abandoned, dilapidated wine estate in 1980, renovated the house in 1982–83 and planted the first vines in 1984.

The estate's winegrowing past is recalled by St. Margrethen's 1634 coat of arms, which shows a grape cluster with 17 berries and four leaves. Since 1994 the municipality has received its own site wine, pressed at Schloss Weinberg from the Sonnenhalde parcel and sold each year at the Chräs- und Weinverkauf on the Saturday before the first Advent.

The estate sits on the Wiberg at 546 m, west above the hamlet of Romenschwanden on Romenschwandenstrasse, and is reached by road from St. Margrethen. The courtyard is enclosed by long farm buildings on the west and east sides, with a broad twelve-step outdoor stair leading up to the terrace between the two towers. The site is a working wine estate, so visits depend on the season and the vineyard work.

The estate's wine revival began in 1984, when 0.8 hectares on the adjacent Schlossberg were planted with Müller-Thurgau and Pinot Noir; the first bottling in 1985 yielded just under 330 litres. Since 1994 the Ortsgemeinde St. Margrethen has received its own site wine from the Sonnenhalde parcel, pressed at the estate and sold each year at the Chräs- und Weinverkauf on the Saturday before the first Advent.