Rostov’s impressive Kremlin was built in the 17th century under the orders of the powerful Metropolitan Iona of Rostov. He wanted the town (which in those days still wielded some power in the region) to have one of the most beautiful Kremlins in the country and to that end he dug deep into the church's coffers to build this imposing fortress.
Nowadays within the Kremlin walls there are numerous museums, although unfortunately most of them are of little interest to foreign visitors. It is however well worth climbing up the Kremlin walls and the bell tower, taking a look in the cathedral and checking out the regular art exhibitions.
In front of the Kremlin is the huge 12th century Dormition of Mary Cathedral, which is in essence a working church - although it should be noted that inside it is undergoing a complete renovation. For a small extra fee you can also climb up the adjacent bell tower for a view over the surrounding area.
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.