Marseille's answer to Alcatraz, this brooding island-fortress-prison has hosted victims of religious persecution, roués, anti-royalists, revolutionaries and Alexandre Dumas père's (fictional) hero, the Count of Monte Cristo.
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A THUMBNAIL HISTORY
The Château started life as a fortress. It was built in 1524-31 on the orders of King François I as a defence against attacks from the sea, and was instantly controversial.
Marseille had been annexed to France in 1481, but the city retained in theory the right to provide her own defence. The new Château was to many people an unwelcome reminder of royal, Parisian authority.
And, in the long term, although it successfully repelled an attack on the port by Charles V of Spain in 1536, the cannons gradually proved inadequate to reach invading ships.
So the Château became a prison in the mid-16th century. Among its first guests were a couple of fishermen and one Anselme, a knight accused of plotting against the monarchy who died, strangled, in his cell.
Subsequent inhabitants over the next 200 years included 3,500 Huguenots (French Protestants) who earned their keep as galley slaves and a Monsieur de Niozelles who was given six years for failing to take his hat off in the presence of King Louis XIV.
Others were imprisoned without trial underso-called lettres de cachet, supposedly signed by the King, for minor misdemeanours (a popular ploy used by moneyed families to get rid of unruly offspring without causing a public scandal).
The writer and revolutionary Honoré Gabriel Riqueti, Comte de Mirabeau, a legendary ladies' man despite his startlingly ugly looks, did time there in 1774 and promptly seduced the woman who ran the canteen.
His stint inside was to do him no harm: the main boulevard in Aix en Provence was later named after him. Gaston Crémieux, a leader of the Paris Commune was shot there in 1871.
But the Count of Monte Cristo remains the Château d'If's star prisoner, and the key reason for its continuing mystique and fascination.
Dumas (pictured) set his thrilling revenge adventure during the early decades of the 19th century and published it in 18 instalments between 1844 and 1846.
Very often adapted for film and television, it tells of Edmond Dantès, a sailor unjustly accused of treason on the eve of his wedding and holed up for 14 years before becoming the only inmate to escape by swimming across to the city. Today, his exploit inspires an annual swimming race, the Monte Cristo Challenge.
One of the island's most oddball denizens arrived years before the Château was commissioned. A rhinoceros had been presented by the King of Gujarat in India to the King of Portugal who, in turn, decided to pass it on to Pope Leo X.
The ship from Lisbon to Rome, bearing the beast splendidly kitted out in a "gilt-iron chain and a green velvet collar decorated with gilt roses and carnations", had to make a stop-over at If.
Here the rhino remained as an attraction for several weeks, inspiring the German artist Albrecht Dürer to produce a famous woodcut in 1515, pictured below (Dürer never actually saw the animal but worked from various second-hand descriptions). Alas, the ship bearing the rhino onward to Rome was wrecked en route and the animal was presented to the Pope as a stuffed trophy.
The CHÂTEAU D'IF
Dripping with history and brooding atmosphere, the Château d'If is itself an impressive sight and the boat ride across from Marseille makes for a delightful day trip. But little effort has been made to maximise its incredible story.
Many of the printed explanatory signs are in French only (though you are given quite an informative leaflet on the way in).
A number of cells are simply shells, even if it's spookily fun to imagine oneself a prisoner there; some of the display cabinets are empty. There's a small presentation on the history of the rhino and an inevitable gift shop.
But you can tour through cells of different sizes, some of them - so-called pistoles which were rented at a premium by richer prisoners - relatively luxurious, with fireplaces and high ceilings. You can also climb up to the top of one of the towers for terrific 360 degree views of the bay.
A number of panels introduce the colourful figures of Dantès and Dumas, exploring his mixed-race origins (Dumas' grandmother was Haitian). A few rooms have screens playing key scenes from some of the very many film adaptations of The Count of Monte Cristo.
THE OTHER FRIOUL ISLANDS
If is just one of four Frioul Islands. The others are Ratonneau, Pomègues and tiny, inaccessible Tiboulen. Port Frioul on Ratonneau is the second stop served by the shuttle boat and the best spot for a lazy day trip. It's the only one of the Frioul Islands to have bars and restaurants.
Pictured: the slightly surreal sight of a 19th century neo-Greek chapel towering above the modern bars and apartments on the waterfront.
A 20 minute walk from the landing stage at Port Frioul, you'll find a small-ish, sandy beach, the plage de Saint Estève, with close-up views of the Château d'If and (in summer) a small snack bar. Though it's quite a trip to get here from Marseille, it's very popular with locals.
In 2010 an experimental "underwater path" was set up at this beach to present the islands' rich marine life. Five buoys roughly 25 metres apart mark five underwater panels explaining (in French) the flora and fauna to be found at each spot. Don't forget your snorkel, flippers and swimsuit if you want to try this out.
A little further on from the plage de Saint Estève is the Hôpital Caroline. As Marseille developed as a port, the islands were used as a stopover for sailors and subsequently a quarantine station to protect the city from epidemics. This impressive structure was built in the early 19th century to treat people suffering from yellow fever.
The Hôpital Caroline is currently in a semi-ruined state and being restored by teams of volunteers. Don't expect this to be completed anytime soon!
For the moment it's closed to the public except for special events. For instance, each year in July, it provides a magical, open-air backdrop to the popular and long-established MIMI Festival of avant-garde music.
Pomègues has quite a different feel: wilder and more unspoiled. Head over here if you are interested in hiking, exploring the extraordinary plants and birdlife and getting away from the crowds.
It's connected to Ratonneau by a long causeway called the Digue Berry and, if you walk along the upper level of this dyke, you will get a fantastic panoramic view of all four Frioul islands at once, plus the Château d'If.
The Frioul Islands represent extreme examples of a Mediterranean habitat. Their fierce little micro-climate has been chiselled by the Mistral wind and blazing sun and they are one of the driest sites in France.
Consequently, they have developed some 350 rare species of plants, including varieties of samphire, sea lilies and sea lavender: come in spring to see them at their best before they shrivel in the midsummer drought.
The islands are also home to birds such as the bluebird, kestrel, peregrine falcon, little owl and yellow-legged gull, known locally as le gabian. If you read French, you can learn more about all this natural heritage on a series of enamel plaques dotted around Pomègues.
How to get there and get around: A regular shuttle boat leaves from the Old Port (near Norman Foster's big stainless steel sun canopy) all the year round, weather permitting. It doesn't run on Mondays outside the tourist season or on days of high winds. Note that not all of the boats shop at the Château.
Entrance to the Château is charged extra when you get there and the whole package can be quite expensive, through there are reductions for groups and families.
The journey takes about 20 minutes to If and 30 minutes to Port Frioul. Details of the Frioul boat shuttle. It's possible to buy tickets in advance online to avoid having to queue at the booking office on the day.
All the islands are entirely pedestrianised except for service vehicles and, on Ratonneau, a petit train (little tourist train) which, in July and August only, runs between Port Frioul, Saint Estève beach and the Hôpital Caroline.
You can walk this same route easily in 20-30 minutes but it's a hot slog in the middle of summer and there is little shade along the way.
Where to stay: There is nowhere to stay on any of the islands. But that may be changing soon. The leading Marseille-born designer and artist known as Ora Ïto has bought a large plot of land on Ratonneau around the fort of Brégantin at the western edge of the island and plans to turn it into an open-air art centre and small upscale hotel.
Inevitably locals are sceptical about the project but Ïto has already transformed the roof terrace of Marseille's Radiant City into an acclaimed and successful art gallery, so the signs are good.
Where to eat and drink: The island of If has one small snack bar / restaurant, with superlative views (and correspondingly high prices); it closes in winter. If not planning to eat there, visitors are strongly advised to bring their own refreshments, at least water, as If can get extremely hot in the fierce midsummer sun.
On Ratonneau, there is a convenience store and a dozen or so restaurants and brasseries all lined up along the harbour front. They serve simple food but it can be surprisingly good, and good value too (this is more likely in our experience the further you walk from the landing stage).
In summer the ferries to the mainland run late enough to have dinner there. At lunchtime, a more attractive option might be a picnic at Saint Estève beach or in one of the islands' many delightful creeks.
There is no bank or cash dispenser / ATM on the islands, so come with good supplies if you intend to buy a drink or ice-cream.
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