Jelení Street belongs to one of the streets from which you can access the Prague Castle complex. If you are going to the Prague Castle by tram, you should get off at the tram stop Pražský hrad (Prague Castle) and walk through U Prašného mostu street to the complex.
For my adventurous spirits we recommend to get off at Brusnice stop and from there take an amazing walk through the small fairy tale like streets of the Hradčany district. This area is referred to as New World - this part of Prague is definitely worth visiting as it offers the most authentic medieval atmosphere in the city. South of the street there is the Deer’s moat, which originally was part of the defensive fortification of Prague Castle, thus the name of the street.