|Length:||7.5 miles (12.1 km)|
|Meets:||A82, B862, B853, B8082, B851|
|Old route now:||B9161, A9|
|Route outline (key)|
The road starts on the A82 in Inverness and initially follows the original route of the A9 into the city centre. This takes it over the Ness Bridge and along Bridge Street before it turns sharp right as it reaches the pedestrianised High Street (where the A9 went ahead). Climbing up Castle Street, the route passes the end of the B853 and then follows Culduthel Road as it weaves through the suburbs of Inverness.
After a couple of miles, it reaches the B8082 at a roundabout next to Inverness Royal Academy, where the two routes cross. The road soon reaches an unsigned TOTSO where it turns right, and immediately narrows to single-track where someone thoughtlessly built a couple of bungalows 30 or more years ago. As it leaves Inverness behind, climbing steadily over Drummossie Muir, the road never really regains a full S2 width, often narrowing to single-track, albeit with hard and frequently used verges which permit two cars to pass at a reasonable speed.
The route climbs to a height of 250 m, higher than the A9 to the east, but slightly lower than General Wade's military road between the two. After a relatively level section across the summit, the road starts a gentle descent to the River Nairn, which is reached after a couple of sharp bends, and crossed by Balnafoich Bridge. Soon after, the B861 terminates on the B851 in the small, scattered village of Tombreck.
Before the A9 was extended north in 1935, all roads to the north of Inverness were in the 8 zone. As a result, the B861 originally started at Munlochy on the A833 (now A832) and used the Kessock Ferry to reach Inverness. Sometime in the mid 1920s, the route was extended southwards, probably at around the same time that the A862 was created, spawning a number of new B roads on the south/eastern side of Loch Ness.
The original part of the route was renumbered B9161 in 1935, when the old A88 became the A9, with the B861 surviving from Inverness southwards. Then, when the Kessock Bridge was opened, some of the B861's original route on the north of the Beauly Firth became a heavily upgraded A9, whereas the section to the south was declassified.