There are two places where it makes sense to provide out-of-the-box partial support for mapping in EFES: on the search results page and on individual inscriptions/texts.

EFES shouldn't provide place information of its own, and there isn't a single nice method for automatically harvesting desired information from external sources. It's up to the documentation to point the way forward, and the simplest approach is to advocate downloading data dumps of RDF from appropriate sources and loading them into EFES' Sesame repository.

The problem with writing queries and renderings of this RDF data is that no two sources of data ever manage to use the same ontology/ontologies. It may be necessary to create a mapping ontology just to get latitude and longitude predicates consistently queryable!