| RHP417 | Plan of the estate of Scotscalder, Caithness | 1802 |
| RHP528 | Plan of line of March from Loch Olginey to Loch More as determined by Judicial referee, Caithness | 1864 |
| RHP667 | Plans of the controverted ground betwixt the lands of Clayock, Knockdee, and Stemster with the conterminous lands, Caithness | c 1770 |
| RHP667/1 | Plans of the controverted ground betwixt the lands of Clayock, Knockdee, and Stemster with the conterminous lands | c 1770 |
| RHP667/2 | Plans of the controverted ground betwixt the lands of Clayock, Knockdee, and Stemster with the conterminous lands | c 1770 |
| RHP667/3 | Plans of the controverted ground betwixt the lands of Clayock, Knockdee, and Stemster with the conterminous lands | c 1770 |
| RHP1217 | Plan of the estates of Assery, Brawlibin, Lieurary(Lurrery) and Achscrabster, property of Sir John Sinclair of Ubster | nd |
| RHP1218 | Plan of the lands of Brawlbin, Lambsdale and Assery, Caithness | 1866 |
| RHP1218/1 | Plan of the lands of Brawlbin, Lambsdale and Assery, Caithness | 1866 |
| RHP1218/2 | Plan of the lands of Brawlbin, Lambsdale and Assery, Caithness | 1866 |
| RHP1679 | Plan of [Torran Water] part of River Forss above Loch Shurrery, Caithness | 1887 |
| RHP1681 | Plan showing marches of crown lands at Dorrery, Caithness | [c 1864] |
| RHP2776 | Plan of the lands of Dorrery, Halkirk, Caithness | 1848 |
| RHP2777 | Plan of the lands of Dorrery, Halkirk, Caithness | 1848 |
| RHP2778 | Plan of the lands of Dorrery, Halkirk, Caithness | 19th century |
| RHP2779 | Plan of the lands of Dorrery, Halkirk, Caithness | 19th century |
| RHP2780/1-2 | Plans of march between the lands of Dorrery and Scotscalder, Halkirk, Caithness | 1850 |
| RHP2781 | Plan of the lands of Dorrery, showing various proposed boundaries according to the crown and other landowners. | nd |
| RHP2782/1-2 | Bound Ordnance Survey 6 inch plans showing the march between the lands of Dorrery and Shurrery | 1902 |
| RHP2783 | Ordnance Survey 6 inch plan (Caithness, XXI) marked to show march between the estate of Dorrery and the estate of Murkle | 1903 |
| RHP2784 | Ordnance Survey 6 inch plan of the lands of Dorrery, showing boundaries of estate as adjusted | 1903 |
| RHP2785/A-B | Ordnance Survey 1/2500 and 6 inch plans of the estate of Scotscalder , Halkirk, Caithness | 1911 |
| RHP2797 | Plan of aqueduct from the south end of Loch Calder to Thurso, prepared in connection with deed of wayleave to Thurso Police Commissioners. | 1876 |
| RHP4418 | Plan of the Forss estates, Caithness | 1919 |
| RHP4418/1 | Plan of the Forss estates, Caithness | 1919 |
| RHP4418/2 | Plan of the Forss estates, Caithness | 1919 |
| RHP4418/3 | Plans of the Forss estates, Caithness | 1919 |
| RHP6329 | Ordnance Survey 6 inch plan (Caithness, sheets V and XI combined) | c. 1876 |
| RHP11610 | Plan of intended road from the town of Thurso to Dunbeath, Caithness | 1797 |
| RHP11663 | Plan of two roads from Drum Hollistan to Thurso. | 1809 |
| RHP11664 | Plan of intended road from Dunbeath to Thurso. | 1809 |
| RHP11692 | Plan of road from the town of Thurso to Halkirk and Achcomhaire (Achorlie). | 1805 |
| RHP15444 | Architectural plan, elevation and section of station house and offices at Georgemas Junction (Sutherland and Caithness Railway): 1872 | 1872 |
| RHP15620 | Architectural plan and elevation of Altnabreac Station buildings (Sutherland and Caithness Railway): 1877 | 1877 |
| RHP18201 | Plan of the Sutherland and Caithness Railway from Thurso to Georgemas Junction. | 1871 |
| RHP20886 | Ordnance Survey 6 inch plan marked to show small holdings of Calder Mains and West Calder | Early 20th century |
| RHP22511 | Plan of Strathmore estate, the property of J.G.T. Sinclair of Ulbster | 1867 |
| RHP35112 | Plan of the estate of Strathmore, showing farm boundaries, acreages, and land use | 1862 |
| RHP38311/5 | L.M.S. Railway, Northern Section: Gradient profiles, stations etc | 1937 |
| RHP38974 | Ordnance Survey 6 inch plan (Caithness, sheets XVI, XVII, XXI and XXII), marked to show ground evicted from Dorrery (relating to the case of Charles Seton Guthrie v. Lord Advocate, 1864), with a shepherd's house and other details at Cnoc-Glas. | 1887 |
| RHP40964 | Plan of line of march between [lands of Dorrery and lands of Olgrinmore, Olgrinbeg and Braehour] in causa Lord Advocate v. Guthrie. | 30 Nov 1863 |
| RHP43417 | Ordnance Survey 1 inch map marked to show parish boundaries and quoad sacra parish of Shurrey. | 1902 |
| RHP43588 | Plan of Halkirk burial ground extension, showing drainage and sections and elevations of wall and gates. | 1938 |
| RHP43651 | Plan of Halkirk Water Supply District. | 1925 |
| RHP43675 | Ordnance Survey 6 inch plan marked to show proposed enlargement of holding on farm of Baillie. | 1913 |
| RHP43679 | Ordnance Survey 6 inch plan marked to show proposed new and enlarged holdings and common land on farm of Lower Westerdale. | 1914 |
| RHP44000 | 1. Xerox copy (2 sheets) of plan of village to be erected at Halkirk. 2. Note of information on reverse of plan. | 1803 |
| RHP44028 | Plan of Torran Water from Cnoc-Glas to Loch Shurrery, showing diverted channels. | 1887 |
| RHP49637 | Ordnance Survey 6 inch plan (Caithness, sheet XVII) marked to show fishings on River Thurso | 1876 |
| RHP78982 | Ordnance Survey 6 inch plan (Caithness, sheet XI) marked to show farm boundaries | [1944-1955] |
| RHP78983 | Ordnance Survey 6 inch plan (Caithness, sheet XII) marked to show farm boundaries | [1944-1955] |
| RHP78986 | Ordnance Survey 6 inch plan (Caithness, sheet XV) marked to show farm boundaries | [1944-1955] |
| RHP78987 | Ordnance Survey 6 inch plan (Caithness, sheet XVI) marked to farm boundaries | [1944-1955] |
| RHP78988 | Ordnance Survey 6 inch plan (Caithness, sheet XVII) marked to show farm boundaries | [1944-1955] |
| RHP78989 | Ordnance Survey 6 inch plan (Caithness, sheet XVIII) marked to show farm boundaries | [1944-1955] |
| RHP78992 | Ordnance Survey 6 inch plan (Caithness, sheet XXI) marked to show farm boundaries | [1944-1955] |
| RHP78993 | Ordnance Survey 6 inch plan (Caithness, sheet XXII) marked to show farm boundaries | [1944-1955] |
| RHP79529 | Ordnance Survey 6 inch plan (Caithness, sheet X) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79533 | Ordnance Survey 6 inch plan (Caithness, sheet XXVI) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79534 | Ordnance Survey 6 inch plan (Caithness, sheet XXVII) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79535 | Ordnance Survey 6 inch plan (Caithness, sheet XXVIII) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79538 | Ordnance Survey 6 inch plan (Caithness, sheet XXXIA) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79539 | Ordnance Survey 6 inch plan (Caithness, sheet XXXI) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79540 | Ordnance Survey 6 inch plan (Caithness, sheet XXXII) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP79544 | Ordnance Survey 6 inch plan (Caithness, sheet XXXVII) marked to show farm boundaries: [1944 x 1954] | nd |
| RHP97562 | Ordnance Survey 6 inch plan (Caithness, sheet X) coloured and marked to show classification of land | [1944-1954] |
| RHP128817 | Hand coloured drawing showing elevation, plan and section of Public Road Bridge over railway at Georgemas Station. (Highland Railway) | 1905 |
| RHP128861 | Hand coloured drawing showing elevation, plan and sections for strengthening of Thurso River Bridge near Halkirk (Highland Railway) | 1908 |
| RHP128862 | Hand coloured drawing showing elevation, plan and section of bridge No 338 over Thurso River near Halkirk (Highland Railway) | 1919 |
| RHP129783 | Hand coloured drawing showing details of steelwork for proposed strengthening of Sligach River Bridge 50 foot span near Altnabreac (The Highland Railway) | 1908 |
| RHP129784 | Hand coloured drawing showing details of steelwork for strengthening Thurso River Bridge near Halkirk (The Highland Railway) | 1908 |
| RHP142371 | Plans of proposed extension to Halkirk burial ground, Caithness | [1968] |
| RHP142371/1 | Halkirk burial ground, Caithness: location plan | [1968] |
| RHP142371/2 | Halkirk burial ground, Caithness: site plan | [1968] |
| RHP142768 | Ordnance Survey 1 inch plan (Reay, sheet [-]; Wick, sheet 116) | c 1910-c 1924 |
| RHP142772 | Plans of Dorrery and Scotscalder estates, Caithness | 1916 |
| RHP142772/1 | Ordnance Survey 6 inch plan (Caithness, sheet XI) | 1916 |
| RHP142772/2 | Ordnance Survey 6 inch plan (Caithness, sheets XVI & [-]) | 1916 |
| RHP142772/3 | Ordnance Survey 6 inch plan (Caithness, sheet XXI) | 1916 |
| RHP142772/4 | Ordnance Survey 6 inch plan (Caithness, sheet XXII) | 1916 |
| RHP142811 | Plans of Scotscalder estate, Caithness | c 1907 |
| RHP142811/1 | Ordnance Survey 6 inch plan (Caithness sheet XI) | c 1907 |
| RHP142811/2 | Ordnance Survey 6 inch plan (Caithness sheet XVII) | c 1907 |
| RHP142811/3 | Ordnance Survey 6 inch plan (Caithness sheet XXI) | c 1909 |
| RHP142811/4 | Ordnance Survey 6 inch plan (Caithness sheet XXII) | c 1908 |
| RHP142811/5 | Ordnance Survey 6 inch plan (Caithness sheet XXVI) | c 1909 |
| RHP142812 | Plans of Lythmore estate, Caithness | c 1906 |
| RHP142812/3 | Ordnance Survey 1 inch map (Caithness sheet X.4) | c 1906 |
| RHP143000/3/23 | Ordnance Survey 1 inch map (Sheet 110, [Latheron]) | 1877 |
| RHP143000/3/28 | Ordnance Survey 1 inch map (Sheet 115, [Reay]) | 1878 |