The operator of the Sofia subway launched a new 6.5-kilometre mainline on Friday, extending to 31 kilometres the total length of Sofia's subway network.
The new subway section has seven stations and was co-financed under the EU-funded operational program Transport, the transport ministry said in a statement.
European Commission president Jose Manuel Barroso was on hand for the opening ceremony, saying that the EU has provided 50% of the necessary funds, or 476 million euro ($599.3 million), the commission said in a separate statement.
The subway operator has ordered eighteen new trains, worth 153 million levs ($98.7 million/78.2 million euro), to service the new mainline. They are manufactured by a tie-up between Russia's Metrovagonmash and Japan's Hitachi.
Following the extension, Sofia's subway network has 27 stations.