The Guardian travelled 100 miles along the EU’s longest river, where some residents are struggling to secure drinking water For centuries, the rock was seen as a warning. When it began to emerge from the Danube, beneath Gellért Hill in Budapest, it meant the river had fallen so low that floating mills could no longer operate, crops were probably failing, and hunger would almost certainly follow. That is why, in the Hungarian capital, where over time the boulder became little more than a legend, it was named Ínség-szikla – the Rock of Starvation. Today, amid record-low water levels on the Danube, the rock has not only emerged from the water, but surfaced almost in its entirety, along with the sandy riverbed on which it rests, astonishing geologists and government scientists sent to examine