Ishak Pasha Palace is one of the most famous palace in Turkey and located 5km far from Dogubeyazit, Agri.
First, you need to go to Agri, one of the province in the eastern side of Turkey. There is Agri Ahmed-i Hani Airport that you can use when coming from cities like, Istanbul and Ankara and Adana. There are other airports in cities, like Kars, Erzurum and Van that you can use but Agri is the most convenient one.
You can also arrive in Agri from all provinces by bus. However, if you are coming from Istanbul, it will take around 30 hours to arrive.
After you come to Agri, just ask for the ring services to Dogubeyazit. It will take about one hour to arrive in Dogubeyazit. Then, you can ask for a taxi to bring you to the Palace.