| RHP11602 | Plan of intended road from the Kirk of Farr to Helmsdale, Sutherland | 1794 |
| RHP11604 | Plan continuing the intended Portenleik road from eastward of Dunrobin to Dunbeath. | 1794 |
| RHP11682 | Plan of the Sutherland Coast Road from Drummuie (Drumbuy of Rhives) to the Ord of Caithness. | Early 19th century |
| RHP11693 | Plan of intended road from Golspie to Dunbeath. | Late 18th century |
| RHP129778-129779 | Two hand coloured drawings showing details of steelwork for strengthening of Craggie River Bridge, 2 miles south of Kildonan (The Highland Railway) | 1908 |
| RHP13254 | Plan of Helmsdale Harbour: 1891. | 1891 |
| RHP17824 | Tracing plan (2 copies) of land required from the Duke of Sutherland by the Highland Railway at Helmsdale Station. | 1919 |
| RHP28016 | Sectional plan of the Sutherland Caithness Railway from Helmsdale Station to beyond Forsinade Station: [c1871 or post] | c 1871 |
| RHP36133/1-3 | Plans of various railway works to be undertaken in terms of the British Transport Commission Provisional Order. 1. Plans and sections 2. Duplicate 3. Book of reference | 1950 |
| RHP38052 | Plan of Helmsdale Bridge showing spot where body of Catharine Ogg was found | 1817 |
| RHP38053 | Architectural drawing of toll house at Helmsdale Bridge | 1817 |
| RHP38300 | Ordnance Survey 1/25000 plan | nd |
| RHP38303 | Ordnance Survey 1 inch map marked to show area of proposed afforestation survey. | nd |
| RHP47692 | Bound plans of British Transport Commission acquisition of lands at Helmsdale Station, near Figgate Burn, culvert near Currie House and additional lands at Birky Side | Nov 1950 |
| RHP79380 | Ordnance Survey 6 inch plan (Sutherland, sheet XXXVI) marked to show farm boundaries | [1944-1955] |
| RHP79387 | Ordnance Survey 6 inch plan (Sutherland, sheet XLV) marked to show farm boundaries | [1944-1955] |
| RHP79388 | Ordnance Survey 6 inch plan (Sutherland, sheet XLVI) marked to show farm boundaries | [1944-1955] |
| RHP79389 | Ordnance Survey 6 inch plan (Sutherland, sheet XLVII) marked to show farm boundaries | [1944-1955] |
| RHP79398 | Ordnance Survey 6 inch plan (Sutherland, sheet LV) marked to show farm boundaries | [1944-1955] |
| RHP79399 | Ordnance Survey 6 inch plan (Sutherland, sheet LVI) marked to show farm boundaries | [1944-1955] |
| RHP79400 | Ordnance Survey 6 inch plan (Sutherland, sheet LVII) marked to show farm boundaries | [1944-1955] |
| RHP79408 | Ordnance Survey 6 inch plan (Sutherland, sheet LXV) marked to show farm boundaries | [1944-1955] |
| RHP79409 | Ordnance Survey 6 inch plan (Sutherland, sheet LXVI) marked to show farm boundaries | [1944-1955] |
| RHP79410 | Ordnance Survey 6 inch plan (Sutherland, sheet LXVII) marked to show farm boundaries | [1944-1955] |
| RHP79411 | Ordnance Survey 6 inch plan (Sutherland, sheet LXVIII) marked to show farm boundary | [1944-1955] |
| RHP79417 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXVI) marked to show farm boundaries | [1944-1955] |
| RHP79418 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXVII) marked to show farm boundaries | [1944-1955] |
| RHP79419 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXVIII) marked to show farm boundaries | [1944-1955] |
| RHP79420 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXIX) marked to show farm boundaries | [1944-1955] |
| RHP79425 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXXIX) marked to show farm boundaries | [1944-1955] |
| RHP79426 | Ordnance Survey 6 inch plan (Sutherland, sheet XC) marked to show farm boundaries | [1944-1955] |
| RHP81159-81160 | Plans (from Ordnance Survey) of Suisgill Estate and Helmsdale Fishings for sale | 1973 |
| RHP84469 | Architectural plans, elevations and sections, with site plan, of Kilournan railway cottage in connection with proposed addition, water supply and drainage [London Midland and Scottish Railway] | [c 1923] |
| RHP84665 | Architectural plans, elevations and sections, with site plan, of Kilournan railway cottage in connection with proposed addition, water supply and drainage (British Railways) | [c 1948] |
| RHP84740 | Architectural plans, elevations and section, with block plan, of Kilournan railway cottage in connection with proposed addition, water supply and drainage [London Midland and Scottish Railway] | [c 1923] |
| RHP84747-84748 | Architectural plans, elevations and sections of stationmaster's house at Helmsdale (London Midland and Scottish Railway) | [c 1923] |
| RHP93953/28 | General plan of Helmsdale Harbour | Feb 1955 |
| RHP94218 | Plan of boundaries at Kildonan Station (British Railways) | 7 Nov 1949 |
| RHP94516 | Plan and gradient profile of signalling arrangements at Helmsdale South Signal Post (British Railways) | Sep 1955 |
| RHP97528 | Ordnance Survey 6 inch plan (Sutherland, sheet LXXXIX) marked to show classification of land | [1944-1954] |
| RHP97529 | Ordnance Survey 6 inch plan (Sutherland, sheet XC) marked to show classification of land, Sutherland | [1944-1954] |
| RHP129780 | Hand coloured drawing showing details of steelwork for strengthening of Free River Bridge, 3 miles south of Kinbrace (The Highland Railway) | 1908 |
| RHP129781 | Hand coloured drawing showing details of steelwork for strengthening Helmsdale River Bridge, 2 miles south of Kinbrace (The Highland Railway) | 1908 |
| RHP129782 | Hand coloured drawing showing details of steelwork for strengthening of Bannock Burn Bridge, 2 miles north of Kinbrace, (The Highland Railway) | 1908 |
| RHP131823 | Elevation, plan and sections of a bridge carrying the A9 road over the railway at Helmsdale Station (London Midland and Scottish Railway) | 1933 |
| RHP143400/4/9 | Ordnance Survey 6 inch plan, Sutherland, Sheet NC 91 NW | 1970s-1980s |
| RHP143400/4/10 | Ordnance Survey 6 inch plan, Sutherland, Sheet NC 91 NE | 1970s-1980s |
| RHP143400/4/11 | Ordnance Survey 6 inch plan, Sutherland, Sheet NC 92 SW | 1970s-1980s |
| RHP143400/5 | Ordnance Survey National Grid Square ND | 1970s-1980s |
| RHP143400/5/1 | Ordnance Survey 6 inch plan, Sutherland, Sheet ND 01 NW | 1970s-1980s |
| RHP143400/5/2 | Ordnance Survey 6 inch plan, Sutherland, Sheet ND 01 SW | 1970s-1980s |