The Château d'Étampes was a castle in the town of Étampes. The principal remains are of the 12th-century keep, the Tour de Guinette.
The Château d'Étampes was an early 10th-century stronghold of Robert the Pious, King of France, that comprised both a palace proper and motte. Between 1130 and 1150, a new castle was created overlooking the valley, culminating in a strong keep or donjon: the present Tour de Guinette. The Château was extended under later kings, notably Philip II of France, but suffered through sieges in the Hundred Years War before having been ordered destroyed by Henry IV of France, after which only the keep remained.
The architectural aspects of this former royal castle are known from contemporary images, including the Très Riches Heures du duc de Berry. Tour de Guinette was in the center of the castle and was surrounded by a rectangular curtain wall punctuated by corner towers. This wall was, in turn, enclosed by two additional walls providing layers of defense for the keep.
The surviving keep stands roughly 27 meters tall and is a quatrefoil plan (much like a four-leaf clover). Divided into four stories, first-floor access may originally have been reached from the enclosure wall. This interesting plan is the result of tactical experimentation that the keep underwent during the mid-12th century to improve the defense of towers against missiles and to reduce dead ground. The circular lobes deflect missiles, and allow defenders to cover the foot of the walls from the summit of the keep. The plan resembles the keeps of Ambleny and nearby Houdan. Clifford's Tower, part of York Castle in York, England, is believed to have been inspired by Étampes.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.