In 1492 a fire destroyed the majority of the structures, the residential tower burned out completely, as documented by Johannes Stumpf in his chronicle: Anno domini 1492 verbran das Schloßz zu Ustri in Grund.

Furthermore: Batt von Bonstetten initiated after the fire (Turm oben abwerffen und ein schoen geheüß … drauf setzen) to demolish the upper section of the tower plinth and to add a new, probably half-timbered structure.

At that time the fortification was also surrounded by a wall with battlements, separated by a trench from the eastern slope of the mountain chain towards Oberuster.

[1][3] Between 1917 and 1919 the most recent redesign was carried out, and the tower rebuilt and again sided with a new, historicist superstructure, now a popular vantage point.

Despite the efforts to reconstruct a medieval appearance, the now existing upper part of the castle tower is a bit raw guessed copy of the construction phase around 1529.

[2] There are also about 10 metres (33 ft) long remains of the circular wall at the north, but it's unknown when it was built (1663 or before), as well as the origin of the neighboured barn is not documented.

To take care of the tower's "inhabitants", the public access is limited: From July to the end of October, on Sundays 2 to 5 pm, the castle's tower may used as vantage point overlooking the Glatt Valley and the Greifensee lake shore towards the Pfannenstiel–Forch mountain chain, as well as guided tours of the weapon chamber (Waffenkammer) and the Knights' Hall (Rittersaal) are held.

Some historians suggest a fief of the St. Gallen abbey to the lords of Winterthur after disputes in 1027 AD; the feud later may belong to the Kyburg family, and not, as much of the surrounding area, to the House of Rapperswil.

[2] The Bonstetten family held jurisdiction on the court of Nossikon, another locality of the present city of Uster, and partially of Kirchuster.

Frequent sales followed and one of the next owners, Hans Vogler sold all sovereign rights to the city of Zürich in 1544.

Jakob Heusser-Staub, a fabricant, bought the nearly ruined castle in 1916, financed a reconstruction by the architect Johannes Meier in 1917, and donated the property along with the economic structures to the citizens of Uster, managed by the Heusser-Staub-Stiftung, a foundation.

Since 1 September 1995 the castle houses the private boarding school Schloss Schule Uster,[8] and the former restaurant Burg was rebuilt in a steakhouse in 2009.