The capital city of the Hittite Empire, Hattusa advanced in art and architecture. Hattusa spreads over a very wide area. The excavations yielded 5 cultural levels. Remains from Hatti, Assyrian, Hittite, Phyrigian, Galatian, Roman and Byzantine periods. The remains consist of the Lower City, Upper City, Large Castle, (King’s Castle), and Yazilikaya. The city rises 300 meters from north to south. The part in the north is called the ‘’Lower City’’ and the part in the south is called the ‘’Upper City.’’ The city is open on the northern side and surrounded by city walls on all sides, other than the northern side. This picture from Yazilikaya reliefs shows Tuthaliya IV with protective god Sarruma. Sarruma is the son of God of Euphrates Teshup and Godddess of Fertility Hepat. Only gods could wear pointed hats, which had hooks on them. You can see the most interesting one of the gates of Hattusa. This gate, known as Yerkapi, actually consists of two doors on top of each other. The underground tunnel under the city walls and under the wall, covered by stones (71 meters long) is the gate of secret entrance to the city. There is the gate with sphinx, entered by going through the city walls, right above it. There are 6 doors known to be used to enter Hittite capital Hattusa. The Upper City, where temples and sacred areas were located, was surrounded by five imposing gates, where lions and sphinxes were on guard at their entrance. Two of the sphinxes at these gates were sent to Germany for renovation before World War Iand one of them was repaired and returned to Turkey but the other one was returned almost 100 years later after long and persistent efforts. This sphinx, with its peer in Istanbul Archaeological Museum, is exhibited at Bogazkoy Museum of Archeology, which has been restored and turned into a cute place in November 2011, in the land it belongs to since the same date.

Yerkapi, which is in the southernmost and highest point of the city, received its name from the only tunnel, which can be entered, in Hattusa.This tunnel leads outside the city walls. There is the gate with the Sphinx in the middle of the city wall, which goes over the mound, created here. Yazilikaya is a Hittite outdoor temple, made between natural rocks 2 km to the northeast of Hittite capital city Hattusa (Bogazkoy) in the province of Corum. Two openings among the rocks (rooms A and B) are carved with reliefs, which depict Hittite gods and is one of the most important monuments from the Hittite period. The large temple extends over a 14.500 m2 area. Rituals and sacrificial ceremonies were held in outdoor courtyards. Cults and provisions, used for rituals were kept in the storage rooms around the temple. They were also used as a storage for grains, wine and oil. Storage rooms, which surrounded the temple had multi stories and it is thought that there were about 200 storage rooms in total. Tablets with cuneiform scripts were found here during the excavations, conducted here in 1907. All the goods, stored in the temple rooms, were recorded. Hattusa's entrance gate and the restored city walls can be seen quite clearly from here. There is a Green Stone, whose function remains unsolved, immediately after entering the Large Temple. Howver, this green stone, believed to be holy, is the largest known one-piece green stone in the world. It is thought that it was found in Egypt and given as a gift by Rameses II.

Protected by two large sphinxes, belonging to the Hittite period, the monumental gat in the south was organized to be between two towers. Parts of the single-piece monoliths, used as door jambs, approximately 2 meters from the ground, were carved in the shape of a sphinx. The large Hittite building complex, entered through this Gate with Sphinx has not been completely excavated. Foundations of a tower, next to the Gate with Sphinx has been covered with many orthostats. Most of the reliefs and sphinxes belong to the 14th century B.C. Most of these have been changed with their replicas and the originals have been transferred to Anatolian Civilizations Museum in Ankara.

One of the most important architectural areas in Bogazkoy is the Large Temple. (Temple No.1) The large temple, which comprises the center of the northern city in Hattusa, was built as a house of Storm God Hati and Sun God of the city of Arinna. The temple has two adytons and there are streets with cobble stones and squares around the temple and storage rooms, which open onto these streets in four directions behind these. The Large temple is surrounded by buildings, which are of secondary importance. The most important one among these is the house on the slope. It stands out with its size, plan and multiple stories. Comprehensive excavations were conducted only in the Inner Lower City part here. Placed on an artificial terrace, which belongs to the Imperial era, i.e. 13th Century B.C., the largest religious building in the city, the large Temple / Temple No. 1 belongs to this section of the city. Most of the residences, whose foundations of walls can be seen to the north of the temple and below the terrace, belong to the same period.