| RHP11600 | Plan of intended roads from Tongue to Portinleck on the Dornoch Firth and from Tongue to Kirk of Farr and thence up Strathnaver to join the Portinleck line of road at the head of Loch Naver. | 1794 |
| RHP11601 | Plan of intended road from Scourie Bay on the North Sea to Portinleck Ferry on the Dornoch Firth. (Vignette of river and deer.) | 1794 |
| RHP11657 | Plan of proposed road from Tongue to Creich | 1809 |
| RHP15637 | Architectural plan and elevation of addition to station building at Lairg (Sutherland Railway): 1872 | 1872 |
| RHP15638 | Architectural plan, elevation and section of Highland Railway waiting shed at Lairg: 1875 | 1875 |
| RHP17450 | Plan of Lairg Station showing land to be acquired from the Duke of Sutherland by the Highland Railway. | 1919 |
| RHP17451 | Plan of the Sutherland Railway from Lairg Station to the Myaulich Burn. | 1865 |
| RHP17839 | Tracing plan (3 copies) of land at Lairg Station to be acquired from the Duke of Sutherland by the Highland Railway. | 1919 |
| RHP22562 | Plan of the marches between the Reay and Sutherland estates in the area between Ben Leoid and Fionn Loch Beag | 1822 |
| RHP35901 | Plan showing the line of pipe tracks, sites of cisterns and 'tap', and proposed enclosures at springs adjoining Loch Dola or Dulaich (part of Sutherland County Council's Lairg Water Supply Scheme). | 1896 |
| RHP35903 | Tracing plan showing the lines of pipe tracks and positions of covered cisterns between Loch Dola or Dulaich and Lairg (Sutherland County Council's Lairg Water Supply Scheme). | 1896 |
| RHP44272 | Ordnance Survey 1 inch map (sheet 102) marked to show farms of Achany, Craggie (Creagach), Gruids and Sallachy (Sallachadh) with shooting-rights pertaining thereto. | 1894 |
| RHP44273 | Ordnance Survey 1/2500 plan (Sutherland, sheet CII.12) marked to show land at and round Achany. | 1905 |
| RHP49100 | Book of reference to plans of diversion of Sutherland Railway near Golspie and Dunrobin Castle, road crossings near Toroboll and at Pittentrail Mills, and alteration of levels at Fleet Mound | 1865 |
| RHP79394 | Ordnance Survey 6 inch plan (Sutherland, sheet LI) marked to show farm boundaries | [1944-1955] |
| RHP79404 | Ordnance Survey 6 inch plan (Sutherland, sheet LXI) marked to show farm boundaries | [1944-1955] |
| RHP79406 | Ordnance Survey 6 inch plan (Sutherland, sheet LXIII) marked to show farm boundaries | [1944-1955] |
| RHP79414 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXII) marked to show farm boundaries | [1944-1955] |
| RHP79415 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXIII) marked to show farm boundaries | [1944-1955] |
| RHP79429 | Ordnance Survey 6 inch plan (Sutherland, sheet XCIII) marked to show farm boundaries | [1944-1955] |
| RHP79430 | Ordnance Survey 6 inch plan (Sutherland, sheet XCIV) marked to show farm boundaries | [1944-1955] |
| RHP79431 | Ordnance Survey 6 inch plan (Sutherland, sheet XCV) marked to show farm boundaries | [1944-1955] |
| RHP79437 | Ordnance Survey 6 inch plan (Sutherland, sheet CIII) annotated to indicate presence of Colorado Beetle in area | [1944-1955] |
| RHP81727 | Plan (from Ordnance Survey) showing boundaries at Lairg Station (British Railways) | 1969 |
| RHP81748 | Profile diagram of bridge no. 170¾ mile north of Lairg [British Railways] | [c 1948] |
| RHP92546 | Copy plan of controverted marches and grazings at Duchally (Douchally) in dispute between Lord Reay and Roderick McLeod of Cadboll | 1766 |
| RHP92547 | Plan of controverted ground at Duchally between Lord Reay and Roderick McLeod of Cadboll, with note added about existence of field book showing how plan was compiled | Jul 1765 |
| RHP94229 | Plan (from Ordnance Survey) of Lairg Freight Sundries Depot (British Railways) | 8 May 1969 |
| RHP97527 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXXV) marked to show classification of land | [1944-1954] |
| RHP97530 | Ordnance Survey 6 inch plan (Sutherland, sheet XCIV) marked to show classification of land | [1944-1954] |
| RHP97746 | Ordnance Survey 6 inch plan (Sutherland, sheet XCV) marked to show classification of land | [1944-1954] |
| RHP126222 | Blueprint showing elevation, plan and section for repairs to Bridge No 186 between Lairg and Rogart (London Midland and Scottish Railway) | 1928 |
| RHP126327 | Drawing showing plan of source of water supply to Lairg Station (London Midland and Scottish Railway) | 1924 |
| RHP131641 | Weight diagram showing elevation, plan and sections of bridge carrying Torroboll Road over railway over railway at 67 miles 58 chains between Lairg and Rogart Stations (London, Midland and Scottish Railway) | c 1933 |
| RHP131642 | Weight diagram showing elevation, plan and sections of bridge carrying Rhianbreck Road over railway over railway at 68 miles 32 chains between Lairg and Rogart Stations (London, Midland and Scottish Railway) | c 1933 |
| RHP142306 | Plans of Lairg burial ground extension, Sutherland | May 1956 |
| RHP142306/1 | Site plan | May 1956 |
| RHP142306/2 | Lair plan | May 1956 |
| RHP143000/3/15 | Ordnance Survey 1 inch map (Sheet 102, [Lairg]) | 1881 |
| RHP143400/8/15 | Ordnance Survey 6 inch plan, Ross and Cromarty; Sutherland, Sheet NH 59 NE | 1960s-1970s |