Highways England says a tunnel would “remove the sight and sound of traffic” from the monument.
Heritage experts have been invited to Stonehenge to see updated plans for a 1.9-mile (3km) road tunnel at the site.
Unesco and the International Council on Monuments and Sites (ICOMOS) will look at ideas to prevent the A303 from splitting the site.
Highways England says one entrance has been moved to avoid conflicting with the winter solstice alignment.
It says the tunnel will also “remove the sight and sound of traffic… from the iconic monument”.
Previously Unesco said a short tunnel could damage the World Heritage Site and a bypass above ground or a longer tunnel should not be ruled out.
But speaking on Twitter, campaigner Andy Rhind-Tutt said he was disappointed Highways England and the Department for Digital, Culture, Media & Sport had not invited landowners to a meeting with ICOMOS and Unesco this week.