Kahta is in Southeastern Anatolia.
Kahta, on lake of Atatürk Dam is a good base to explore the area and Mount Nemrut from, although there's not a lot of life in the town itself.
Indeed Kahta should be the main base for visiting Nemrut. There is also another way to Nemrut from Malatya. However the trip from Kahta to Nemrut will include a sightseeing of Karakuş Hill, Arsemia Castle, and ancient Kahta Castle. All of these attractions are included in the National Park. Hence, a visit to Nemrut is shorter and more valuable if done from Kahta.
There are frequent dolmuş services from Adıyaman, which depart every 15 minutes.
The nearest airport is in Adıyaman, about 15 km away, which has connections from many cities in Turkey. AnadoluJet, which is sub division of Turkish Airlines flies from Ankara ESB International Airport to Adıyaman on Tuesdays, Thursdays and Saturdays. Flights depart at 6:55PM and arrive at 8:05PM to Adıyaman.
There are five bus companies serving Kahta from many cities in Turkey.
You can walk pretty much everywhere in town.
There are plenty of good options for Southeastern Anatolian food. You may try Papatya Restaurant int the city center for kebab and other red meat/chicken food. However do not forget to eat fish at the restaurants in the shore of the Atatürk Dam (Baraj as called in Kahta). Especially Zeynel'in Yeri is good choice. Fish from the dam itself and from Kahta river should be tried. Yayın (a fatty freshwater fish) and Sarıgöz are pretty delicious fish. These restaurants also serve alcoholic drinks, including raki which is a good company with fish.
Plenty of accommodation, but don't trust the hotel managers. Ask around at different offices about the tours to Nemrut, and at the bus station about getting out of town once you're done.
A common scam in the town is that the hotel managers may give incorrect information about bus schedules to make travelers stay at their hotels longer. Double-check with the bus companies yourself.
Having said that, though, Kahta is a fairly safe area. You can just go out, take a walk to Atatürk Dam, have a very nice dinner in fish restaurants just next to the dam, and enjoy the cool air in the night.
Mount Nemrut (Nemrut dagi)
The Mount Nemrut tomb-sanctuary was probably built for king Antiochus Theos of Kommagene who believed he was a descendant of Apollo, in the first part of the first century BC. The main feature is a tumulus (tomb hill) about 50 meters high, underneath which it is thought, the tomb itself is located. It is also thought that it will be as rich as any of the tombs of Egypt.
However, you have to be prepared to get up early (at about 2.30) if you want to see the sunrise. It's quite a distance from the mountain and it's best if you have your own transport or arrange a guided tour.
Around the Tumulus are two main terraces; the big eastern terrace, and the smaller western terrace. These might have been used for religeous and other ceremonies due to the astronomical and religeous nature of the monument. A bas-relief has been found on the western terrace of a lion and the planets Mars, Jupiter and Mercury as they would have been on july 7, 62 BCE, the possible starting date of the complex' construction.
Big seated statues, 8 to 9 meters high of Antiochus himself, Hercules, Zeus-Orosmasdes (associated with the Persian god Ahura-Mazda) and a few other greek and Persian deieties along with two lions and two eagles, line these terraces. Since their erection, the heads have toppeled from the bodies which remain at their original positions and lay scattered throughout the site. In more recent times they have been put back at their assumed original positions (albeit without the bodies) so they can once again face the sunrise and sunset. The arrangement of the statues (or in this case heads) is known as a hierothesion.
Currently, restoration work is being done on the statues which will continue until at least 2010. There are also plans to move at least some of the monuments to a museum.
The Summit is 2150 meter above sea level and provides a great view of the surrounding mountains and even Ataturk lake. The main attraction is to watch the sunrise from the eastern terrace which give the bodyless heads a beautyful orange hue and adds to the sense of mystery of the place.
If going up Nemrut to see the sunrise, bring warm clothing with you because it can get cold up there (even in summer) since the summit is at about 2150 meters.