The Palace or Fortress of Buyukkale contains the ruins at least two structures, the earliest from the pre-Hittite period, with a Hittite temple built essentially on top of the earlier ruins. Built on the top of a steep cliff above the remainder of Hattusha, Buyukkale was in the best defensible place in the city. The platform includes an area of 250 x 140 m, and included numerous temples and residential structures enclosed by a thick wall with guard houses and surrounded by steep cliffsides.
The most recent excavations at Hattusha have been completed at Buyukkale, conducted by the German Archaeological Institute on the fortress and some associated granaries in 1998 and 2003. The excavations identified an Iron Age (Neo Hittite) occupation at the site. For a plan of the fortress, as well as a reconstruction, see the official Hattusha website. You can also find a report of the excavations, albeit in German.
The most recent excavations at Hattusha have been completed at Buyukkale, conducted by the German Archaeological Institute on the fortress and some associated granaries in 1998 and 2003. The excavations identified an Iron Age (Neo Hittite) occupation at the site. For a plan of the fortress, as well as a reconstruction, see the official Hattusha website. You can also find a report of the excavations, albeit in German.