An extensive Iron Age cemetery lies at the west end of the common, and it includes the graves of wealthy individuals.
Built over the top of it is a Roman settlement in an excellent state of preservation.
“This is a site of European importance,” said former Guernsey Museums director Dr Jason Monaghan.
Pictured: Excavations took place on Longis Common in 2019.
Previous excavations have revealed well-preserved Roman buildings and courtyards dating from the second to fourth centuries AD.
During 2022, Dr Rob Fry from Reading University, assisted by the Guernsey Museum Archaeology Group, conducted a survey using ground penetrating radar.
It confirmed there is a dense concentration of archaeological features extending over two hectares.
Dr Phil de Jersey of Guernsey Museum said: “We aim to find out more about the people who lived here and why such a small island has such a concentration of archaeology. The evidence so far points to Alderney playing a key role in the trade routes that ran along the Atlantic coast of France for over a thousand years.”
Pictured: Archaeologists say the site is European importance.
The Excavation will run from Saturday until Friday 27 May, with volunteers from the islands and the UK taking part.
Post-excavation work will continue for the rest of the year.
The project is supported by the States of Alderney, Alderney Electricity and The Alderney Society.
Updates will be posted on the Dig Alderney Facebook page and on Twitter @Digalderney.
Dig Alderney has been established as a Charitable Association to “facilitate and conduct archaeological research on Alderney and support that led by other organisations, in keeping within Alderney’s best interests”.
The project is run by volunteers. Those behind it are keen to discuss partnerships with commercial organisations and private sponsors to support the work.
Main image: the site where the dig will take place.