The Fort of Bost, locally referred to as Qala-e-Bost (Dari: قلعه بست; Pashto: بست کلا), is a fortification near Lashkargah in the Helmand Province of Afghanistan, which is believed by some to have been built approximately 3,000 years ago.

[4] The Fort of Bost is located at 31° 30’ 02″ N, 64° 21’ 24″ E near the convergence of the Helmand and Arghandab rivers, about 6 miles south of Lashkargah.

The site is famous for its 11th century decorative arch, which appears on the 100 afghani note (Afghan currency).

Those who visited the fortress described it as a thriving community, with many fresh fruit and date palm trees in the area.

[5] In 2006, construction began on a cobblestone road to lead from the south of Lashkargah to the Qala-e-Bost Arch (known to readers of James A. Michener's Caravans as Qala Bist.