A cache of documents that make up a census of Budapest’s Jewish population in 1944 before the liquidation of the city’s Jews to Nazi death camps was found hidden in a wall during the renovation of an apartment in the city.

A cache of documents that make up a census of Budapest’s Jewish population in 1944 before the liquidation of the city’s Jews to Nazi death camps was found hidden in a wall during the renovation of an apartment in the city.

The 6,300 documents were uncovered in August, the French news agency AFP reported over the weekend.

The 135 pounds of documents were believed to have been destroyed during World War II.

The papers have been turned over to the Budapest City Archives.

The census forms found in the Budapest apartment contain names of each building’s inhabitants, and whether they are Jewish or not, with total numbers of Christians and Jews marked in the corners, according to AFP. The Jews listed on the forms were later moved into apartments set aside for Jews, who were later moved into the city’s ghetto.

“The content and scale of the finding is unprecedented. It helps to fill a huge gap in the history of the Holocaust in Budapest,” Director of Budapest City Archives Istvan Kenyeres told AFP.

About 600,000 Hungarian Jews died in the Holocaust, most in Auschwitz.