Outer Hebrides: See
Castles: Lews Castle in Stornoway is an Edwardian mansion, now a museum and event space.
Dùn Èistean near the north tip of Lewis is the scraps of a 16th century redoubt, on a sea stack that you reach by footbridge.
Amhuinnsuidhe Castle 15 miles west of Tarbert on Harris is a posh hotel for shooting parties.
Borve Castle on Benbecula is the ruin of a medieval tower house.
Ormacleit Castle on South Uist is the fragments of an 18th century mansion.
Kisimul Castle is a medieval bastion perched on an islet off Castelbay on Barra.
Prehistoric sites abound, as the lack of population and mainland farming methods saved them from plough and pickaxe.
Callinish standing stones on Lewis are the must-see. This is the chief site of a Neolithic ritual landscape, so nearby are Callanish 2, 3 and so on.
Dun Carloway on Lewis is a broch, a sturdy Iron Age fortress.
Bostadh on Great Bernera is an Iron Age house, though the original has been re-buried and you visit a replica.
Pobull Fhinn is the best stone circle on North Uist.
The wheelhouse on Grimsay is Iron Age, probably ritual not residential.
Pollachar standing stone on South Uist is more accessible than most megaliths: they're often on soggy moors.
Blackhouses were traditional Hebridean dwellings, with the cattle kept at one end, and a fug of peat smoke as they had no chimney.
Arnol on Lewis is a blackhouse village - many are ruined but one is restored as a museum.
Garenin is another such village. Some are now holiday cottages and one is a hostel.
The hostel on Bernaray is a restored blackhouse.
Howmore on South Uist has several, and one is a hostel.
Natural world: the islands are good places for birdwatching, with a RSPB reserve on North Uist, and many migrant and resident species. St Kilda is the stand-out if you can reach it.
Seals and occasionally otters can be seen on coastal rocks.
Eriskay has a distinctive breed of wild pony.
The brief summer brings out wild flowers, most colourful on the machair, the sandy terrain near the beaches.
Dark skies in winter display a profusion of stars and sometimes the aurora. But not in summer, as it never gets properly dark.
Local culture: and note the museums above.
Museum nan Eilean is in Stornoway, and An Lanntair is an art centre there.
Taigh Chearsabhagh is a cultural centre in Lochmaddy on North Uist.