The Château de Montlhéry played a key role in France's history, dating back at least as far as 1008 when Thibaut, a forester under Robert II, built the first known fortifications. Of vital significance, due to its strategic location between Paris and Orleans, the first castle was destroyed between 1104 and 1107.
The lords of Montlhéry opposed the king, Louis VI, who had the castle destroyed but left the tower standing. The castle we see today was built in the early 13th century under Phiippe Auguste. Louis IX, who was later to become king, took refuge there during the revolt of the barons until the Parisians came to Montlhéry on foot to escort him back to Paris. Legend has it that in 1254, on his return from one of the Crusades, Saint Louis expressed his gratitude with the construction of a chapel bearing his name, which stood at the castle entrance. (The foundations are still visible to the left of the drawbridge.)
In 1347, the castle came under siege and was occupied by the English several times. It is likely that major repair work was carried out in 1382 by the constable Olivier de Clisson, who was the castle's chief guard at the time. Additions included four extra floors in the keep, a wall walk, and several fireplaces. The castle was a strategic target for ransackers interested in the region, and the residents of Montlhéry grew weary of being robbed and seeing their homes pillaged. In 1591, under the reign of Henri IV, they were granted the right to disarm the castle which, from then on, was used as a quarry and its stone contributed to all kinds of buildings.
During the 19th century, the site was used for scientific research purposes.
César François Cassini de Thury: measurement of the speed of sound in air.
Crançois Arago: in 1822, measurement of the speed of sound in air via experiments carried out between Villejuif and the Tour de Montlhéry tower.
Marie-Alfre Cornu: calculation of the time taken by a ray of light to make a return trip between the Tour de Montlhéry and an identified point of the Paris observatory (300,400 km/s).
Height of the Tower: 30 metres / base 137 metres above sea level
Listed as a Historical Monument in 1840
From 16/04 to 29/10/2023, every Saturday and Sunday between 2 pm and 6 pm.
Full price: 3 €.
Free entry for children - 6 years.