Cracks - some several meters long - have appeared in the 2- year- old Holocaust memorial in the heart of Berlin. Fissures in 393 of the 2,711 concrete slabs that make up the Memorial to the Murdered Jews of Europe will need to be filled with synthetic resin before winter, memorial director Uwe Neumaerker said Tuesday. "The synthetic resin needs to be filled into the cracks to keep more water from penetrating the slabs," Neumaerker said. "We hope that afterward one won't be able to see those white calcium deposits anymore that have been created by the water." He said the cracks did not threaten the stability of the slabs. The site will remain open during the repair work. Designed by the American architect Peter Eisenman, the $38.14 million memorial - a vast field of gray slabs located around the corner from the Brandenburg Gate - opened to the public in May 2005. The memorial is a labyrinth of narrow rising and falling pathways in a field of concrete slabs. The tomblike slabs range in height from 50 centimeters to 4.7 meters. It was not clear how the cracks developed but "there are a few construction sites nearby which could have caused the cracks," Neumaerker said. Vibrations from the new US embassy building and a suburban railway tunnel could have affected the site, Neumaerker said. Neumaerker could not say how much the restoration would cost but city official Manuela Damianakis told the Berliner Zeitung newspaper that Geithner Bau, the company that built the slabs, would have to pay for the restoration. Damianakis and the company could not immediately be reached for comment. An estimated 3 million people visit the monument every year, and more than 1 million visitors have registered at the site's underground information center, according to the foundation that runs the memorial to the Nazis' estimated 6 million Jewish victims.