The Aqueduct of Valens was a Roman aqueduct system built in the late 4th century AD, to supply Constantinople – the capital of the Eastern Roman Empire. Construction of the aqueduct began during the reign of the Roman emperor Constantius II (r. 337–361) and was completed in 373 by the Emperor Valens (r. 364–378). The aqueduct remained in use for many centuries. It was extended and maintained by the Byzantines and the Ottomans.
Initially, the Aqueduct of Valens carried water from springs at Danımandere and Pınarca; the channels from each spring met at Dağyenice. This 4th-century first phase of the system was 268 kilometres long. A second, 5th-century phase added a further 451 kilometres of conduits that took water from Vize, 120 kilometres away from Constantinople.
The final and most visible aqueduct bridge in the system survives in the Fatih district of Istanbul, Turkey. It is an important landmark in the city, with its arches passing over Atatürk Boulevard. The Bozdoğan Kemeri spans the valley between the hills that are today occupied by the Istanbul University and the Fatih Mosque, formerly the site of the Church of the Holy Apostles. The surviving section is 921 metres long, about 50 metres less than the original length.
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.