Depending on your interests I've grouped sites worth seeing:
Historic HighlightsBannockburn, Glencoe, Stirling Castle, Edinburgh Castle, Scone Palace, Culloden, Arbroath Abbey
I include Hadrian's Wall although in England.
Architectural HighlightsNew Lanark, Culross, Inverary, Edinburgh New Town, Scottish Parliament, Glasgow School of Art, Hill House and Mount Stuart, Bute
Archaeological sites
(This extensive tour involves travelling to the Outer Hebrides and Orkney)
Callanish, Skara Brae, Maeshowe, Ring of Brodgar, Standing Stones of Stenness, Dun Carloway Broch, Antonine Wall, Hadrian's Wall, The Scottish Crannog Centre, Clava Cairns; Dunnadd Hill Fort, Kilmartin Glen
How we used to liveGlasgow Tenement & Peoples' Palace, Glasgow; Highland Folk Museum, Newtonmore; Black Houses,Gearrannan Lewis; Fife Folk Museum; Culross, Fife; The Scottish Crannog Centre, Kenmore; Gladstone land, Tolbooth and Huntley House Museums, Edinburgh,
TransportSteam train trips, various; Transport Museums of Bo'ness and Glasgow; Museum of Flight, East Lothian; Discovery Dundee; the paddle steam ship 'Waverley'
Engineering MarvelsForth Bridges, Tay Bridge, Falkirk Wheel, Caledonian Canal, Cruachan Power Station, Pitlochry Hydro Scheme; Glenfinnan Viaduct; Verdant Works, Dundee; National Museum, Edinburgh
Major Art CollectionsEdinburgh: National Galleries of Scotland, and City Art Centre
Glasgow: Burrell Collection & Kelvingrove Art Gallery
Dundee: V&A at Discovery Point
Religious CentresIona; St Margaret's Chapel, Holyrood Abbey, St, Giles Cathedral, Greyfriars Churchyard, Edinburgh; Arbroath Abbey; Dunkeld Cathedral; Glasgow Cathedral; St Andrews Cathedral; The Borders Abbeys: Melrose, Kelso, Jedburgh and Dryburgh,
Royal ConnectionsStirling Castle, Edinburgh Castle, Holyrood House, Balmoral, Glamis Castle, Castle of Mey, Linlithgow Palace, Dunfermline Abbey and Palace, Falkland Palace, Scone Palace, Royal Yacht Britannia, St Andrews
Whisky: You are never far from a distillery
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