Molenberg, Protected hill in Sint-Denijs-Boekel and Zwalm, Belgium

Molenberg is a narrow cobbled road that climbs from Moldergem to the top at 56 m, southwest of Sint-Denijs-Boekel's centre. The roughly paved surface has an average gradient of 7%, with the steepest section at 14.2% in a right-hand bend. At the foot stands the 13th-century Moldergemmolen water mill.

The hill takes its name from the Moldergemmolen, a water mill built at its foot in the 13th century. The cobbled road of the Molenberg was protected as a monument in 1995. Since 1983 the climb has featured 39 times in the Tour of Flanders, first as an early climb and later further into the route.

The cobblestone road surface of Molenberg holds official protection status as a landscape monument, preserving its traditional characteristics for future generations.

The climb runs about 460 metres from the Smarre road up to the top at 56 m, with an average gradient of 7%. The steepest section, 14.2%, comes in the middle at a right-hand bend, so riders should pick a gear before the slope starts. The cobbles are rough and narrow; the parallel Caildenberg offers an alternative route.

The Molenberg has been climbed 39 times in the Tour of Flanders between 1983 and 2016 and again from 2021 to 2025, traditionally as the first or one of the first climbs of the race. Its steepest point, 14.2%, comes in a right-hand bend halfway up the narrow cobbled road.