Serbian archeologists and engineers are working on a hologram to be projected over the Danube river to reproduce parts of a Roman bridge that once stood on the spot, project director Miomir Korac said.

"The hologram will show a replica of the original bridge for a length of 150 to 200 metres (yards)," Korac told AFP.

"We will install pumps that will spray a fine mist of water droplets which will allow the laser to project the image of the bridge," he explained.

The original structure built in 105 AD by emperor Trajan on a supply route for the Roman legions fighting in Dacia province was 1,135 metres (3,724 feet) long.

Although demolished some 150 years later, it held the record for more than 10 centuries as the longest arch bridge to have been built.

The Serbian team will also make a 50-metre miniature mock-up of the bridge near the site of the entrance pillars still visible on the Serbian side of the Danube.

"It is time to restore this site which when it was constructed was a world wonder," Korac said.

The plans for the hologram bridge are part of a larger project to put the spotlight on Serbia's Roman heritage and make a special tourist route mapping the sites, called in Latin the Itinerarium romanum Serbia.

The project which will cost a total of 13 million euros (17.5 million dollars) has received funding from the European Investment Bank (EIB) and a consortium of European banks.

"The idea is to spruce up all these sites so that they can receive tourists by late 2012 and highlight that 18 Roman emperors were born in this territory, including Constantine the Great," the first to convert to Christianity, Korac said.