Geo-spatial applications need to provide powerful search capabilities to support users in their daily activities. However, discovery services are often limited by only syntactically matching user terminology to metadata describing geographical resources. We report our work on the implementation of a geographical catalogue, and corresponding semantic extension, for the spatial data infrastructure (SDI) of the Autonomous Province of Trento (PAT) in Italy. We focus in particular to the semantic extension which is based on the adoption of the S-Match semantic matching tool and on the use of a faceted ontology codifying geographical domain specific knowledge. We finally report our experience in the integration of the faceted ontology with the multi-lingual geo-spatial ontology GeoWordNet.