Fountain in front of the Opera House

The Poltva River once ran in the open through the center of Lviv, but as the city's population grew, the narrow waterway became increasingly polluted. Beginning in 1839, the Austro-Hungarian authorities started channeling the Poltva into purpose-built underground tunnels that merged the river with Lviv’s sewage system, designed by William Heerlein Lindley. in 1900 the Poltava river running through the historical center was hidden in the underground. After the Nazi invasion of the Soviet Union in 1941, the tunnels of the Poltva became a lifeline for hundreds of Jews fleeing the Nazi ghetto and mob violence meted out by some Ukrainians in Lviv. In September 2021, explorer Oleksandr Ivanov used the memoirs of a Holocaust survivor to locate the place where a group of Jews from the Lviv ghetto were hiding during the Nazi occupation. After a year of searching, the explorer uncovered a space cluttered with books, a bottle of German beer, and a heavily rusted electric flashlight, among other items.