Usakli Hoyuk (also known as Kusakli, Kusachakly, Uçaklı) is located at Büyüktaslik Village in the district of Sorgun, Yozgat Province, Turkey, to the north of Mount Kerkenes.

The settlement started at the end of the 3rd millennium BC, and continued through the Middle to the Late Bronze Ages, which witnessed the greatest urban development of the site.

Iron Age (8th-6th centuries BC) city walls were excavated comprising a strong defence system with high ramparts erected using large stones.

Some other scholars also visited this location later,[6] but the whole situation was clarified only by Geoffrey D. Summers in 1993–1994, who did a complete archaeological survey and mapping of the site.

[7] Excavations undertaken at Usakli during 2018 revealed a world's oldest mosaic stone floor associated with a large building of Hittite date.

Since the edges of the mosaic are aligned exactly parallel to the outer walls of the entire building, it can be assumed that it was all created at the same time during the Hittite era.

Stone-covered floors are also known from the Hittite sites at Kuşaklı (Šarišša), Šapinuwa and Ḫattuša, but Uşaklı is the only known example from this period for a mosaic-like layout.

Prior to this, the earliest known mosaic in Anatolia was thought to be a burnt structure in the so-called Burned Building in Phrygian Gordion.