First City

From Memory Alpha, the free Star Trek reference

The First City of the Klingon Imperial Empire was located on Qo'noS and was the location of the Great Hall, where the Klingon High Council met. The city itself is divided into quarters. (TNG: "Sins of the Father")

Kahlest was a resident of the Old Quarter. (TNG: "Sins of the Father") The House of Duras resided within the city. (TNG: "Redemption") The House of Kozak had it's ancestral home within the city. (DS9: "The House of Quark")

"Looking for par'Mach in All the Wrong Places" implies that the Great Hall was located in Qam-Chee, which may be the Klingon name for this city.