Visit What to see Memorial gardens Children's memorial This memorial to the young people murdered in the Holocaust is being built slowly over time, by visitors to The National Holocaust Centre and Museum. Visitors are invited to select a stone from the trough and place it on the memorial, in tribute to one of the 1.5 million individual children who died. The meaning of the stones Why are stones placed on Jewish graves? This is not because of any religious rules, but is an ancient tradition with several possible explanations and it most likely continued for a combination of reasons. In areas where it is difficult to bury a body deep in the ground, one way to protect the remains from scavengers such as wolves is with a pile of heavy stones. Over time, stones need to be replaced as part of regularly maintaining the grave.