Bona Lighthouse, Caledonian Canal

Bona Lighthouse stands on a peninsula at Loch Dochfour, at the north end of Loch Ness, where the water narrows before flowing into the Caledonian Canal. Designed by Thomas Telford around 1815 and altered to function as a lighthouse circa 1848, it is a Grade B listed building of considerable historical importance.

The structure comprises a two-storey octagonal former dwelling and lighthouse with various single-storey storage and stable additions extending to the north and east, all enclosed to the rear by a high coped rubble wall. The buildings are predominantly rendered white. The octagonal ground floor features shallow round-headed recesses with window openings in alternate bays, while the first floor has square recesses in the alternate bays. A first-floor oriel window to the west originally contained the light. The slate roofs are predominantly piended, and there are three coped stacks with clay cans. The former stable area at the end of the north-west range retains its original setts and central drainage channel. The interior was not inspected in 2013, and all windows are currently boarded up.

The building's octagonal form is reminiscent of Telford's tollhouse designs in Shropshire and Wales, where similar polygonal structures appear along main roads. A comparable octagonal tollhouse attributed to Telford exists at Conan Bridge, and another near Tore. The position at this pinch point in the river, with its protruding front bay and former stables, may suggest the building once served as a toll house, though this remains unproven.

Originally constructed as a dwelling house and store, the building contained a bedroom over a ground-floor kitchen in the octagonal space, with a single-storey store and stables to the left and a single room to the rear. Documentary evidence indicates four stables, suggesting Bona functioned as a stopping point along the canal route. The site itself holds historical significance: it occupies the location of Bona Ferry crossing (from "Bon Ath," meaning white ford), which once served drove roads and followed a General Wade road through to Dores. By 1848 it was established as a pier for ferries, and by 1864 it was rebuilt in stone.

In 1844, canal engineers deepened and widened the Bona channel and raised water levels on the loch, marking the transition from horse-drawn barges to steam tugs. Following improvements to the canal at Fort Augustus in 1847, the Bona building was converted to serve as a lighthouse, acting as a visual aid to guide vessels from Loch Ness into the narrow canal channel. Inland lights are uncommon in Scotland, but a significant proportion of those existing are located along the Caledonian Canal network, including the pepper-pot lighthouses at Fort Augustus, Corpach, and Gairlochy. Although Bona was not purpose-built as a light, it appears to have been intended as a viewpoint from its inception.

The Caledonian Canal itself, of which Bona Lighthouse is an integral part, was designed by Thomas Telford following his 1802 report to Government commissioners. Construction began in 1804 with Telford as principal engineer and William Jessop as consulting engineer. The canal, stretching 60 miles from Inverness to Corpach near Fort William, connects four lochs—Loch Dochfur, Loch Ness, Loch Oich, and Loch Lochy—with only 22 miles being man-made. Built to accommodate sea-going vessels, including Royal Navy frigates of 32 and 44 guns, the canal was engineered on a much larger scale than other British canals, with locks that were the largest ever constructed at the time. Despite slow initial progress due to rising costs and difficult conditions, the first complete journey was made on 23-24 October 1822. Though never a commercial success and troubled by problems requiring repairs and improvements in the 1840s, the canal became popular with passenger steamers, and tourism increased following Queen Victoria's visit on 16 September 1873.

The entire Caledonian Canal is a Scheduled Monument of national importance to Scotland (Scheduled Monument No 6498). As one of five surviving canals in Scotland, it is unique in being the only one entirely funded by public money. The canal formed part of a wider Highland infrastructure initiative intended to facilitate trade and industry growth, and most significantly, to address emigration resulting from the Highland Clearances by providing employment.