In December of 2003, a portion of the plaster Exhibit Hall ceiling at the Wagner Free Institute of Science fell two stories, causing concern as to the stability of the remaining plaster. Replacement of the entire plaster ceiling was suggested as a response to the fallen piece and the extent of cracking. While plaster, as a finish material, is often considered replaceable and may not be considered a high priority for conservation, the Exhibit Hall ceiling is historically significant and worth preserving. For a site of historic significance such as the Wagner, total replacement should only be considered if the ceiling is in imminent danger of falling and if the current conditions cannot be successfully mitigated by more sensitive conservation methods such as reattachment.