Église de Rochefort-en-Yvelines, church located in Yvelines, in France

Église Saint-Gilles-et-de-l'Assomption is a fortified Romanesque church built into the hillside at Rochefort-en-Yvelines. Its rough light-grey stone facade has a large circular window with dark glass and stone tracery, flanked by two vertical pilasters, with a narrow slit window to the right and a cross at the gable apex. A smaller stone structure on the left, with a round-arched green door and a bell-cote, stands beside the main building. The interior comprises a single nave, a choir and an apse, plus the later Chapelle des Princes.

Gui I of Rochefort built the church on the hillside, originally with a single nave, choir and apse, dedicated to Saint Giles. A side chapel dedicated to the Virgin was added later, leading to its consecration to the Assumption. The Chapelle des Princes was added to receive the burials of the Rohan family until 1793. The south side door was listed as a monument historique on 1 February 1937.

The church was first dedicated to Saint Giles alone; the addition of a side chapel to the Virgin led to its second dedication to the Assumption, and both names are still used. The Chapelle des Princes, added later, held the tombs of the Rohan family until 1793. The Rochefort cemetery lies against the church.

The church stands on the flank of the hill, and the Rochefort cemetery is directly adjacent to the building. The south side door, listed as a monument historique since 1 February 1937, is the element to look for on the exterior. A subscription was opened in the 2020s to fund upkeep, so parts of the building may be under maintenance.

The south side door was listed as a monument historique by decree of 1 February 1937, the only protected element of the church. The building is Romanesque and fortified, and the adjoining Rochefort cemetery borders it directly. In the 2020s a subscription was opened to fund its upkeep.