I think that is why Bram Stoker decided when he was writing Dracula to build up the nature element to the area- it is a wonderful place in terms of natural beauty. The looming cliffs and mountains and the dark forests. It proved to be exactly what a reader would want in something dark. However, Transylvania has more to offer a tourist than legends and castles, many of the plants and animals who live in the area are, sadly, endangered.
Stoker was Irish so perhaps the land was a type of romantic feel for him since it may have reminded him of home. It probably did not mean much to him about environmentalism as it does today. Many castles in the area are on protected grounds and the peoples of the area use tourism as a means to gain income. Romania itself is a wonderful place to go and see and part of it is because of Transylvania.
There are other legends that can be found there as well. When reading Robert Browning's Pied Piper re-reading the last verse about where people came from this is not found in every edition of the Pied Piper, but if it an interesting one to read if you do find it. The idea then flow that from the German Saxons who, according to Browning, came to the land beyond the forest and remained there-- coming out of a hill, which the poet suggests was the place where the Pied Piper lead the children to. The people built houses and farms and large cities, but unlike the Pied Piper, they were invited by a King of Hungary to help defend the land.
This makes for great writing, and this is the foundation I am looking to build on when writing a book on Transylvania. It is important to understand the legends and the peoples before you can build on the places and give the readers more.