Les Gorges du Verdon
Edouard Martel may have spearheaded modern speleology, and he may have officially been trained as an attorney, but he is the first to have thoroughly explored and reported on the Gorges du Verdon, the "Grand Canyon of Europe".
Martel thought the Verdon the most stunning of canyons. Few dispute this today. The Gorges du Verdon is the largest canyon in Europe, carved up to 700 meters deep into limestone rock. From atop the Route des Crêtes on the northern section, the green Verdon river looks like a tiny grass snake wiggling along.
In the 1920s a handful of vista points were built along the canyon, mostly for the intrepid explorers as access was still difficult. Soon after WWII, the D71 road was constructed along the southern ridge. It's only in 1973 that the road on the northern ridge of the canyon was carved and set-up (the D952). Since then, many have enjoyed visiting by care, as well as on foot, on rafts, by bike and motorcycle (Verdon is a big motorcycle place).
How's the road?
Comfortable. Sure, it winds around. Given the geology, you expect a road that turns, and you'll spot an occasional rock that jumped the cliff to land on the road. You drive slowly and stop frequently to take in the view, so turns aren't as much of an issue as some folks make it to be. The real issue is mid-summer traffic when crowds pack the entire area. Visit the Verdon before July 1 or after August 25 if at all possible.
The traditional loop around the Gorges du Verdon begins from Castellane
and meanders along the gorges' northern rim on the D952 to Moustiers Sainte Marie. Count on a half day journey to enjoy it. The return loop heads from Moustiers to Aiguines to Trigance to Castellane on the D71, D90, D995. The southern ridge is a bit less crowded. There's no reason to stick to this counter-clock direction, mind you. Loop it whichever direction suits your trip. The only one-way loop is the Route des crêtes off the D952 on the northern section.

How long is the drive around the Verdon canyon?As long as possible. Seriously, you might circle around the Verdon north and south in a full day. You would amazed, but dizzy and dazed. With the largest canyon in Europe, best to take your time and soak it all in.
My recommendation? Take 3 days and 2 nights to visit Castellane, Rougon, to stop at the best vista points, to hike a bit along the Point Sublime and on the many marked trails, to experience Moustiers Sainte Marie at nightfall, to ride a pedal boat at the Lac Saint Croix (not when windy, unless you're Tour de France material), to enjoy it when goats block your passage on the canyon road rather than cringe because you're late.

What are the best spots?I've underscored what I would consider must-see's. You could easily spend a week to explore more. What's more, the western side of the gorges is also the eastern edge of some of Provence lavender country (Valensole plateau) so a whole other world of possibilities opens up in May, June and July before lavender harvest.
For a view over the raw plunging cliffs of the Verdon you'll have to stop to the edge of the canyon, at Point
Sublime off the D952 on the northern ridge.
It's at the cross road with the street that heads up to the
village of Rougon. Perched in the sky and hovering above the entrance
to the Verdon Gorges, Rougon is worth a visit. If you're up to it, hike
up from Point Sublime to Rougon. It's 3 km or a half hour's hike. You'll feel like an eagle. There's also a good hike from Point Sublime down the canyon. I've not done it, but clearly it must drop and climb a little...
Back on the D952, just before the village of La Palud sur Verdon, the Route des Crêtes loops around the canyon's crest-line for 25 vista-peppered kilometers. Not too many miles, but with all of its "belvedere" view points from the top of the canyon, count on a full hour.
With a little luck, Eurasion Griffon Vultures (Gyps Fulvus) will circle above your head before it returns to its nests in the cliffs. It's a scavenger who catches hot air currents and glides over the gorges in
search of meat. This bird of prey prefers rabbits and wild boars to humans ;-). It was re-introduced in the Gorges
du Verdon in 1999 and early 2000. The vultures too seem to love the Verdon.
Continuing west on the D952, you might spot a little road-side cabin that sells lavender pouches, and honey and oil.
You reach an intersection at the end of the gorges: left for the Lac du Verdon for a refreshing dip in the bright green waters or right to experience Moustiers Sainte Marie.
Moustiers Sainte-Marie is magical in the evening when the sun sets on the surrounding gold-colored cliffs. It's full of little restaurants, some of them better than others. We like the Treille Muscate for its location right above the river and in the center of town.
A dip in the Sainte-Croix lac feels very refreshing and many family-run outfits rent pedalos, kayaks and windsurfers on the beaches along the lake. A pedal boat and a good set of legs will make for a fun tour of the lake. If interested, I recommend you rent from the outfits at the northern section of the lake (by bridge off D957) so you can more readily access the Verdon river, its caves and waterfalls.
For the full loop around the canyon, head back on the southern rim by charming Aiguines, on the Route de la Corniche Sublime (D71) then enjoy the Balcons de la Mescla vista spot where the Arturby river flows into the Verdon, then Trigance. From Comps, depending on your next destination, you can head back up to Castellane, take the D955 down to Draguignan or the D21 toward Grasse.
Do you have a map for the route you describe above?
For a map of the Gorges du Canyon loop described above, click on the below Google map.
View AzurAlive.com: Gorges du Verdon in a larger map