The Italian anti-corruption Act (law n. 190/2012) requires all public administrations to spread procurement information as open data. Each body is therefore obliged to yearly release standardized XML files, on its public website, containing data that describe all issued public contracts. Though this information is currently available on a machine-readable format, the data is fragmented and published in different files on different websites, without a unified and human-readable view of the information. The ContrattiPubblici.org project aims at developing a semantic knowledge graph based on linked open data principles in order to overcome the fragmentation of existent datasets and to allow easy analysis and the reuse of information. The objectives are to increase public awareness about public spending, to improve transparency on the public procurement chain and to help companies to retrieve useful knowledge for their business activities.