The toblerone trail, which snakes its way from the forests of the Jura mountains to the shores of Lake Geneva, reveals an important part of Switzerland's heritage - but it has nothing to do with chocolate making.
The toblerones in question are anti-tank defences built by the Swiss to slow up any possible invasion by the Nazis during the Second World War.
These 16-tonne concrete obstacles sprouted like giant regimented mushrooms throughout Switzerland 60 years ago, but the line that covers the 10 kilometres from Bassins, in the Jura mountains, to the lakeside near Prangins, is the best preserved.
"This project started as an attempt to preserve an important part of our military heritage," says Gérald Berutto, the driving force behind the scheme and president of the Toblerone Trail Association, without whose intervention this distinctive part of the canton Vaud countryside might well have been demolished.
"But as we've continued, we've realised that the environmental aspect is just as important," he says. The 3,000 toblerones, many of them now covered in moss, ivy and brambles, provide an ideal home for many animals.
The official name for these defences was the Promenthouse Line, named after one of the three rivers along whose course the toblerones run - the others are the Combe and the Sérine.
The trail may only be 15 kilometres long, but a varied landscape awaits walkers, from the broad-leaf forests and babbling brooks of the Jura foothills, through vineyards, orchards and cornfields and down to the lakeside, with its magnificent views of Mont Blanc.
The toblerones used to extend 50 metres into the lake, to prevent an amphibious assault on Switzerland.
Berutto and his colleagues have cleared a well-marked path through the undergrowth and farmland from Bassins to Nyon, as well as putting in steps and bridges. The lower section of the walk, and the facilities on it are accessible for wheelchair users.
Role during wartime
The main objective is educational: to ensure that this priceless military heritage is preserved for future generations. A website has been created specifically to give teachers background information about the military history, geology and ecology of the walk before they bring school trips.
"We have to remind young people about the war, that Switzerland was a small island in the middle of Europe, and their grandfathers and great-grandfathers were ready to defend it with their lives," Berutto explains.
The installations also prove that, despite being neutral, Switzerland did play a role in the war. It had already seen neutral Belgium and Norway invaded, and feared that it could be next.
The country's defence strategy - of which the Promenthouse Line was a vital component - was a classic example of military expediency. In building the line between Bassins and Nyon, the authorities were effectively saying that Geneva was expendable.
The reason was that the Promenthouse-Sérine valley was the first natural barrier that an army invading from the west would encounter. Geneva, surrounded on three sides by occupied France, would have been almost impossible to defend.
One of the highlights of the walk is the Villa Rose, a mysterious pink house that sits alongside what used to be the main road between Geneva and Lausanne. For decades, it puzzled locals: it was clearly well maintained, but there was never a light in the windows and no one was ever spotted entering or leaving.
Those mobilised during the wartime mobilisation knew, however, that this was a fortress - one of 12 that run along the length of the toblerone trail, and one of two that have been renovated by Gérald Bérutto and his association.
On entering the villa, you realise why its purpose was shrouded in secrecy. The ground floor is a veritable arsenal, with large anti-tank cannons protruding in all directions through small holes in the 2.5 metre-thick walls. The windows one sees from the outside are false.
Throughout the war, 20 to 25 soldiers were be holed up in the villa, with no contact with outside world, apart from a military telephone. They would stay there for weeks at a time, waiting for the Germans to invade.
Thanks to the advice of veterans who actually served in the Villa Rose, most of whom are now in their mid-80s, the basement living quarters are exactly as they were in the 1940s, from the gas masks to the washing powder. Even the labels on the wine bottles are from the period.
"One former soldier told us it was exactly as he remembered it, but that one thing was missing - there were no playing cards on the table," Bérutto, himself a former colonel in Switzerland's militia army, says.
The Villa Rose now sits close to an exclusive golf course: a bunker alongside the bunkers, in fact. One wonders how many putts have been missed in the knowledge that an armour-piercing machine gun is trained on the greens.
Another fortress has also been restored to its former condition. The intention is to devote this concrete bunker to the period of the Cold War, when these defences continued to play an important role.
The Villa Rose, which was used by the army until as recently as 1994, and another villa fortress along the route have been listed as protected buildings - among the most recent to acquire this status in Switzerland.
"There are no other buildings like this in the country," Bérutto says, explaining that he hopes the whole toblerone line will be accorded official protection in the near future.
Along the route are many other treasures, from a castle made entirely of wood in Promenthoux to the national museum at Prangins. The route is dotted with mills - the association is busy compiling a complete list - small dams and hydroelectric power stations, testimony to the importance of water in Switzerland.
Bérutto has succeeded in enrolling the support of environmental groups, forestry and fishery officials, as well as the army, and information boards are springing up along the route. It is not necessary to do the entire walk in one go: the organisers have ensured that railway stations and post bus stops are never far away.
by Roy Probert