The integration of data from distributed sources within and among different public authorities is an important aspect on the agenda of e-government. In this paper we present a specific data integration scenario at the Municipality of Bozen-Bolzano, where data from different sources have to be joined via addresses of citizens. We analyze in detail the problems which arise in this scenario. We show that addresses can be represented in a tree structure, and hence, the problem of matching addresses can be reduced to approximate tree matching.