The 600m bridge will connect the Slovakian town of Komarno and the Hungarian town of Komarom. The deal is worth just over €91 million and construction will take 33 months, according to Hungarian media.
The project has suffered several delays because of changes to procurement rules in Hungary which has pushed back completion from mid-2019 to sometime in 2020 after 33 months of construction.
The two cities, although divided by the Danube, have at times been one city under various central European kingdoms.
In March last year, the European Commission approved around €100 million towards the estimated €117 million for the project. Hungary will get €52.5 million and Slovakia will receive €47.6 million under the EU's Connecting Europe Facility.
Construction will start by the end of this year. The project was delayed temporarily by changes to procurement rules in Hungary. The bridge is expected to be complete in the second quarter of 2019.
Komárno is Slovakia's principal port on the Danube. It is also the centre of the Hungarian community in Slovakia, which makes up around 60% of the town's population.
Hungary’s Komárom and Slovakia’s Komárno are also connected by a more recently built so-called lifting bridge.
In 1892 Komárom and the then town of Újszőny were connected by an iron bridge and in 1896 the two towns were united under the name Komárom within the Austro-Hungarian empire. But after the empire was split, the towns developed separately in Hungary and Czechoslovakia.