THERE ARE FOUR ROUTES YOU CAN FOLLOW FROM RUMELI HISARUSTU TO DISCOVER ISTANBUL:

43R (RUMELI HISARUSTU - KABATAS) 
R.HISARUSTU-ETILER-LEVENT-ZINCIRLIKUYU-BESIKTAS-KABATAS 

59R (RUMELI HISARUSTU - SISLI) 
R.HISARUSTU-ETILER-LEVENT-ZINCIRLIKUYU-MECIDIYEKOY-SISLI 

59RS (RUMELI HISARUSTU - SARIYER)
R.HISARUSTU-ETILER-4. LEVENT-MASLAK- HACIOSMAN-SARIYER 

559C (RUMELI HISARUSTU - TAKSIM) 
R.HISARUSTU-ETILER-LEVENT-ZINCIRLIKUYU-BESIKTAS-TAKSIM

YOU CAN ALSO USE SUBWAY AND METROBUS TO TRAVEL AROUND IN ISTANBUL.