Transylvania was once part of the defunct Austro-Hungarian Empire (until the end of World War I). Now it is located in Romania, a country in Europe. In this region is the fictional location of Castle Dracula.
Transylvania bounded on the East and South by the Carpathian mountain range, historical Transylvania extended in the west to the Apuseni Mountains; however, the term frequently encompasses not only Transylvania proper, but also the historical regions of Crişana, Maramureş, and (Romanian) Banat.
In the Marvel Universe, Diablo has spend centuries in Transylvania.