Next to the former "Kartaus," at Niederwaldstraße 7 in Hallgarten, stands the most significant architectural monument of the German democracy movement of the 19th century, the former Itzstein manor house. From 1832 to 1847, secret parliamentary conferences took place here, which can be seen as a precursor to the first German National Parliament in Frankfurt (1848/49). The "Hallgarten Circle," organized by Johann Adam von Itzstein (1775-1855), included figures such as Robert Blum, Johann Jakoby, Friedrich Hecker, Fr. Daniel Bassermann, Heinrich v. Gagern, Hoffmann von Fallersleben, and Rudolf von Gottschall.

In the 17th century, the estate belonged to the Mainz family Hardy. Between 1820 and 1830, all the estate buildings were rebuilt by Peter von Itzstein. In 1875, the winery came into the possession of the princely family Löwenstein-Wertheim-Rosenberg.

After being leased to the nearby Vollrads Castle for nearly 20 years, it has been operated as a private estate again since 1997.

The manor house is now privately owned.