WARSAW, Poland -- The International Auschwitz Council agreed Tuesday to modernize a 51-year-old exhibition at the site of the Nazi death camp and build walls to prevent the ruins of gas chambers from sinking into the ground.

The decision to renovate and preserve remains of the vast Nazi death camp in southern Poland marks a change in the long-standing approach to maintaining the site, which has been left as the Allies found it when they liberated the camp at the end of World War II.

But two of the gas chambers are slowly sinking into the ground and will likely slide out of sight within the next two decades if nothing is done. How to save them prompted debate on the council, with a majority favoring a Polish expert's proposal to halt the erosion by building walls sunk into the ground on either side of the slipping chambers.