Built heritage preservation has been dominated for a long time by classical workflows using paper documents and especially hand drawn maps. Today, digital workflows are adopted in which domain experts record the damages of buildings and the preservation measures with special-purpose documentation software. The resulting maps are rather complex digital documents: they combine geometric data produced with CAD software and thematic data stored in an ontology. In this paper, we discuss some of the problems of long term preservation of such digital maps.One problem in the domain of built heritage preservation is the existence of multiple, inconsistent metadata schemas. We argue, that the problem is essentially an ontology alignment problem and that methods developed there are usable to solve the format mapping problem. We also illustrate with an example, why fully automated alignment is not possible in general and human interaction is typically required.