Fallavier, a castle at the heart of regional history, dominating the plain of the Lower Dauphiné!
Perched at the western end of the Relong hill, separated from the rest of the hill by a wide moat, the site of the ancient castle (and town) of Fallavier today comprises a powerful circular keep, around which are organized the castral buildings (large hall called "aula", chapel, bedrooms, kitchen and stables) surrounded by a first enclosing wall forming a chemise and delimiting a high courtyard.

The second wall once housed a dense group of residential buildings and, on the slope, the former village, now completely destroyed. Still in ruins at the beginning of the 20th century, the building was extensively restored (all the upper parts of the enclosure walls and keep were rebuilt) in the 1970s by its former owner.

History: Although the existence of an earlier fortification is not known, mention of a "mandement" at Fallavier is attested to as early as 1175 in the cartulary of the Abbey of Note-Dame de Bonnevaux. The history of the château is better known today, and is linked to the financial difficulties of the de Beauvoir family and the rivalries between the lords of La Tour, the future dauphins, and the House of Savoy. The architectural features of the original part of the keep point to the end of the 13th century as the date of construction, which is confirmed by archives attesting to extensive work carried out in 1280 by the mason Tassin de Saint-Georges for the House of Savoy.

The châtellenie remained Savoyard until 1355, when the Treaty of Paris established the borders with Savoy. It was then entrusted by Charles V to the Count of Geneva after 1369, and returned to the Delphinian domain in 1391.
In 1593, the lands of Fallavier were sold to François de Bonne, Seigneur de Lesdiguières, thus leaving the royal domain for good.
The Rolland family acquired the ruins of the building in 1891. One of their descendants, Gabriel Mérard, surrounded himself with volunteers and, from 1969 onwards, devoted himself to the reconstruction and rebirth of this edifice. Since 1992, the commune of Saint-Quentin-Fallavier has owned the château and is responsible for its conservation and enhancement.