Bran Castle was a Knights Templar creation. At the time, it was built to protect the access to Western Europe from the Mongols from the East, however, it was not finished until after the Knights Templar were forced to leave Transylvania.
Over time it fell into ruin. (This is a photo of one of the many walls-- the entire castle did not become this!)
After Transylvania became a part of Romania, Queen Marie undertook a rebuild of Bran Castle -- similar to what she did in the city of Alba Iulia. This was one of the palaces she lived in as both Queen of Romania and Dowager Queen of Romania ( After the death of her husband King Ferdinand in 1927).
This did not happen, but Bran Castle is still a large and important tourist destination in Transylvania, and in Europe as well.