Kisimul Castle was built in the 1400s
A historic clan stronghold in the Western Isles is to undergo conservation and archaeological work.
Barra's Kisimul Castle dates from the 15th Century and was built on a rock in a bay as a Macneil power base.
Members of Clan Macneil and Historic Scotland have raised £200,000 for the planned work.
Historic Scotland, which looks after the property, hopes that archaeologists will uncover new clues to castle life in the Middle Ages.
Any new evidence would help to fill large gaps in knowledge about Kisimul.
There are few castles of this nature in Scotland - Ian Walford, Historic Scotland
A fire in the 1700s is believed to have destroyed all written historical records about the fortification.
Its location on a rock in the sea also meant medieval chroniclers were unable to visit the castle to document it.
Historic Scotland took over responsibility for managing and conserving Kisimul in 2000.
At the time the government agency signed a 999-year lease from Ian Roderick Macneil, 46th Clan Chief, for £1 and an annual rent of a bottle of Talisker whisky.
Rory Macneil, the latest clan chief, has welcomed the new investment in the castle.
He said: "I would like to express my gratitude to clans people whose contributions to the Kisimul Castle restoration fund can now be put to good use, and to Historic Scotland for its stewardship of the castle over the past 13 years."
Ian Walford, chief executive of Historic Scotland, described Kisimul as a "true icon of the Western Isles".
He said: "There are few castles of this nature in Scotland, sitting proud in the island's main harbour and for most visitors it is their first experience of Barra's historic environment.
We are delighted to be launching this plan
"Working in partnership with Macneil of Barra, this plan will conserve and enhance a truly magical site in a spectacular Scottish setting for future generations to come."
Western Isles MSP Alasdair Allan, MP Angus MacNeil and Barra councillor Donald Manford have praised the latest effort to conserve the castle.