The European Commission said it approved a 42.5 million euro ($53.4 million) grant for an upgrade of the public transport in Bulgaria's capital Sofia.
With the money Sofia will build a smart public transport management system, purchase 50 new trolleybuses and build and modernize tram lines, the Commission said in a statement on Wednesday.
Bulgaria will contribute with 7.5 million euro to the project.
The investment is part of the European Union's initiative for the reduction of greenhouse gas emissions at European level. Similar projects are being implemented in the Bulgarian cities of Varna, Ruse, Stara Zagora and Pleven.
The city of Sofia has also received 340 million euro from the EU for the expansion of its underground railway network.