Fort Kosmač (Montenegrin: Tvrđava Kosmač, Тврђава Космач) was the southernmost fortress in the Austro-Hungarian Empire, guarding the southern extremity of the border between the empire and Montenegro. It is situated on a hilltop overlooking the road between Budva on the coast and Cetinje, the Montenegrin capital at the time. Constructed in the 1840s, it was attacked during an 1869 rebellion and was garrisoned by Austrian troops until the fall of the empire in 1918. After passing to the newly established Yugoslavia, it was garrisoned again by Italian troops for a period in the Second World War. The building is now abandoned and in a ruinous condition.