Poland officially opened the 672km A4 Autostrada that runs through southern Poland from the border with Germany to that with the Ukraine.
The motorway passes through major Polish cities including Wrocław, Katowice and Kraków.
Work started in the mid-1980s on various sections and continued piecemeal over the years. In the 1990s, after political change to a more open market economy, plans proceeded to finish the route by 2013.
The completion date was moved forward after Poland became joint host, along with Ukraine, of the 2012 UEFA European Football Championship. There was an urgency to complete road infrastructure projects, according to a report by Radio Poland.
But a June 2012 date to open the route proved too ambitious and then further delays, including some caused by major floods in 2010, pushed back the completion date.
There is still some work to do on two motorway services that likely will be ready by the end of October.