Round Brittany from Cherbourg

Climb the steep stair called the Gouffre into the abbey's salle des Gardes, then work round the Merveille on the north side to stand under its eastern gable and the tapering tour des Corbins, and pick out the gilded Saint Michael on the spire 157.10 m above the shore

In the Scriptorial, work through the display of the abbey's library — more than 200 medieval volumes — and find the copies in which the Mont's monks were reading translations of Aristotle, Boethius, Cicero and Plato

Walk the whole 1,754 m circuit of the ramparts, counting the nine gates you pass over, and look inwards as you go: the walls came through the American bombardment of August 1944 almost untouched, and the town inside them was rebuilt afterwards in an old style but not stone for stone, so almost everything below you is younger than the wall you are standing on

Walk the 2,600 m of rampart walk round the old town and name the nine towers as you pass them — Beaumanoir, Vaucouleurs, Saint-Julien, Beaufort, du Connétable, de Coëtquen, Penthièvre, Longue and Sainte-Catherine — and find all five gates, including the Porte Saint-Louis cut through in 1620

At the stalls on the Port de la Houle, buy a dozen flat oysters and a dozen cupped ones and eat them side by side on the slipway: the flat ones are the oysters that won Cancale its town charter from François I in 1545, when the aldermen of Paris had them delivered twice a week, and the biggest wild ones were known as pieds de cheval, horses' hooves

Walk the GR34 customs path from Ploumanac'h round to Trégastel through the granite chaos, and from the Mean Ruz point pick out three things offshore: the château of Costaérès on its island, the Île Renote, and the Sept-Îles with the lighthouse on the Île aux Moines 4.6 km out

Find the tomb of Saint Yves in the north aisle, then stand in Duke John V's funeral chapel built alongside it in 1420 and work out why he put it there: he wanted to lie next to the saint. Look up at its vault keystones, repainted in 1469 with the arms of Duke François II and his wife Marguerite

Walk round the Cairn of Barnenez, 75 m long and 28 m across at its widest, and count the entrances to its eleven passage graves, then look at the quarried west face, where a contractor's excavator cut open chambers A to D in the spring of 1955 and left the inside of the cairn on show

From the square, read the Kreisker tower in its parts: forty metres of solid tower to the open gallery, then thirty-eight metres of pierced spire above it, with four sixteen-metre pinnacles at the corners — and know that its model, Notre-Dame-du-Mur at Morlaix, was pulled down in 1806, a year before Napoleon's decree saved this one

On the 3.5 km crossing from Roscoff's old port, watch the water in the narrow channel: the currents here run hard enough that the boat takes a long dogleg to cover a strait barely a kilometre wide, and divers working this channel in the early 1990s brought up Roman amphorae and pottery from its floor

Walk out to the Pointe de Pen-Hir above 70m of cliff and pick off the six Tas de Pois from the landward one outwards - Grand Dahouet, Petit Dahouet, Penn-Glaz, Chelott, Ar Forc'h and Bern-Id; then find the Croix de Pen-Hir, cut from blue Brennilis granite for the Bretons of the Free French, and read the Breton motto on the back of it, Kentoc'h mervel eget em zaotra, rather death than dishonour

Stand in the nave of Saint-Corentin and sight down it to see the choir swing about 10 degrees to the left, then go outside and find King Gradlon on his horse between the two spires — every 26 July a Quimpérois used to climb up behind him, hold a glass of wine to his lips and throw the empty glass down to the crowd

Visit the Port-musée in Douarnenez, with its traditional boats afloat in the harbour and its museum in a former sardine cannery

Walk the rampart walk round the Ville Close, find the Tour du Fer a Cheval where the 13th-century tower base and 14th-century wall of the medieval enceinte were dug up, and remember the walls were only saved from being sold off and listed in 1899 because the painters who worked here got up a petition

Start at the Maison des mégalithes at Le Ménec and walk the Ménec alignment — inside the rows on a booked commented visit in summer, when the fenced sites are open to 400 people a day, or on your own out of season when access is free — and follow the files far enough to see that they converge rather than run parallel

Walk the Côte Sauvage between the pointe de Beg en Aud and the pointe de Beg er Lan, and on the rock platform at the foot of the cliffs look at how the granite splits: it is a two-mica leucogranite that deformed while it was still crystallising, so it comes apart in parallel sheets five millimetres to a centimetre thick

Walk the length of the four fragments and work out what was done here: a single block of orthogneiss between 300 and 330 tonnes, quarried at least 8 to 10 km away towards Vannes or the Rhuys peninsula, which means it was brought across a stretch of water with a strong current before it was ever stood up

Walk the Séné reserve trails to the hides built so the birds cannot see you, and find avocets and black-winged stilts on the old salt pans in spring, spoonbills and black-tailed godwits on migration, or the December and January peak when the waterfowl crowd the mudflats at low tide

Walk all three enceintes of the château and date the towers by their shape: the earliest are square, the later ones round, and the horseshoe towers were built against the bases of others to give the crossbowmen room to swing. Then look at the stone itself — dressed granite for the corners, local schist rubble for the walls

Take the guided tour of the Cornille-Havard foundry and find the two furnaces they still use: the wood-and-coal double-vaulted reverberatory furnace of 1865 for the big castings and the 1950s one for small bells, with the clay moulds and the casting pit between them. Ask which bell was last poured — this is the workshop that cast the 1.1-tonne peace bell for Bayeux and the bells of Notre-Dame