Below is the map of Greater Romania shown after it gained its territory from the First World War. It is very interesting to note that Transylvania is not as close to the Hungarian borders, but that most people simply call the two smaller provinces ( in particular the Banat) a part of Transylvania. This is where Transylvania is on the map. This would also be the map that the Romanian Royal family would know until 1940 and the beginning of the Second World War.
It is worth noting that many people do not see Transylvania as being so small, and that since they are used to thinking about Romania as being larger, they tend to forget that Transylvania proper is in fact the grey area in the map below. it it also because of the many connections with the Royal families of several countries that Transylvania has so many castles, and also why people seem to think that Romania and Transylvania are larger.