Ćukovac
Ćukovac (Serbian: Ћуковац) is an urban neighborhood of Belgrade, the capital of Serbia. It is located in Belgrade's municipality of Zemun.
Ćukovac is one of several small neighborhoods which constitute the downtown of Zemun, former separate city and today's borough and municipality of Belgrade. It borders the neighborhoods of Gardoš and Muhar (north), Donji Grad (east and south), Kalvarija (south-west), Sava Kovačević (west) and Gornji Grad (north-west). It is generally bounded by the streets of Glavna, Cara Dušana, Bežanijska and Ugrinovačka.
Ćukovac is located on the hill of the same name, one of three hills where the old core of the town of Zemun developed. The other two hills are Gardoš, extending to the north, and Kalvarija, extending to the south, creating a crescent hilly formation. The entirely residential neighborhood is known for its short and narrow streets. Name of the hill and the neighborhood, ćukovac, means the "owl hill" (ćuk, an owl).
However, Ćukovac, Gardoš and Kalvarija hills are not natural features. Zemun loess plateau is the former southern shelf of the ancient, now dried, Pannonian Sea. Modern area of Zemun's Donji Grad was regularly flooded by the Danube and the water would carve canals through the loess. Citizens would then build pathways along those canals and so created the passages, carving the hills out of the plateau. Today it appears that Zemun is built on several hills, with passages between them turned into modern streets, but the hills are actually manmade.
The underground below the hill has been crisscrossed by a network of underground corridors or lagums, dating back from the period of Austrian rule in Zemun. They connect Ćukovac, Muhar, Kalvarija and Gradoš. This terrain is one of the most active landslide areas in Belgrade. Being cut into for centuries, the loess in some sections have cliffs vertical up to 90%. In the previous centuries, settlers left many vertical shafts which ventilated the lagums, drying the loess and keeping it compact. After World War II, inhabitants began to settle Ćukovac hill unaware of the lagums, especially the largest one, which covered an area of 450 m2 (4,800 sq ft). As there was no sufficient sewage system at that time, they built septic tanks and collected rainwater, but also as the ventilation shafts in time were covered or filled with garbage, it all made the ground wet in the course of several decades. The lagums retained the moist and began to collapse. Eventually, the walls and houses became unstable to the point of breaking façades and walls. In 1988 city authorities finally intervened as the houses began to sink in three streets. Holes were drilled to connect the surface with the largest lagum. Altogether, 22 drillings were made and 779 m3 (27,500 cu ft) of concrete were poured into the lagum, filling it until the ground was stabilized, but the lagum was destroyed in the process. Still, the situation is critical after almost every downpour.
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