The Bala Hissar or Citadel of Kabul is one of the largest and most prominent monuments and archaeological sites in the city and of international historic significance. The Bala Hissar of Kabul is sited on an outcrop of a large hill , called today the Sher Darwaza, which borders the older part of Kabul on its south. The site is a natural place for a citadel: high enough to dominate the adjoining town, low enough to sink wells for water. Kabul 's location on a strategic corridor from Central Asia to India ensured that. even when not the primary seat of power, its fortress always had military and political significance. Today the Bala Hissar is still an Afghan military base, whose perimeter fence encompasses nearly the whole of the former fortress, except for a small section in the north-west comer. Between the 16th and 19th centuries, many of the most dramatic events of Afghan and regional history have unfolded within its high fortified walls, as the Citadel was connected with both the rise of the Mughal dynasty and the Anglo-Afghan wars. While little remains above ground today that identifies the Citadel's heritage and glorious past, modern constructions recently built on the site risk further destruction of the archaeological remains from earlier periods of occupation, dating possibly as far back as the 2nd century B.C. Today the Bala Hissar is still an Afghan military base, whose perimeter fence encompasses nearly the whole of the former fortress, except for a small section in the north-west comer. Although the upper fort is in ruins and the lower fort has lost all its walls and former buildings, the whole site has archaeological potential. 

Source: Woodburn, Bill. The Bala Hissar in Kabul: Revealing a Fortress-Palace in Afghanistan (pp. 1-??). In The Institution of Royal Engineers Professional Paper No. 1. 2009.