The Cornish pastiche: Tintagel, a castle on a rocky outcrop, is this Camelot? No, it's not.

The Omphalos, Sandycove, near Dublin is a Martello tower and the setting of the opening chapters of James Joyce's Ulysses. 'Omphalos' is the Greek for 'navel', the centre of the ancient world. Ulysses is a navel novel.

Reg Presley, suddenly rich from the proceeds of a hit song, devotes his money and time to uncovering the secrets of the Warminster Triangle: UFOs, crop circles and the changing shape of planet Earth. Reg is voiced by Long John Silver.

Kathleen Schlesinger, born in Holywood, Belfast, in 1862, was a music archaeologist who published a major study of the ancient Greek wind instrument, the aulos. Her fascination with tuning systems led to lifelong collaboration with Australian microtonal composer Elsie Hamilton. Thanks to Kate Bowan for sending me a copy of her article 'Living Between Worlds Ancient and Modern'.

Silbury Hill - the largest man made mound in Europe, built around the same time as the Great Pyramids, sits on the side of the A4 in Wiltshire. It's a sombre dome, a green whale, an alien submarine. Is it a monument to the Great Goddess? A watchtower? A swollen node on a ley line? No, it's a big cake.

A cuttlefish squirts sepia ink and creates a pseudomorph of itself to divert predators. With a little more know-how it could manufacture 3d sepia images of Weston's Grand Pier, its Big Wheel or Helicopter Museum.

Acton, London W3, where I discovered Welsh writer Arthur Machen in the library, slightly dishevelled, jacket all ripped.

Goat's Hole Cave, Paviland, on the Gower peninsular, south Wales, is the site of a prehistoric ceremonial burial, one of the oldest in Europe and earliest evidence of modern humans on these islands. There are many such caves nearby, eerie, ancient dwelling places, described by the painter Ceri Richards as 'black apples of Gower'.

In Cambridge, looking for the Wittgenstein Archive, we find a brick wall, a skip and a white slip-on shoe.

In Dundee the boots of a seven foot giant stomp up the street. 'Where is my creator?' it howls. Mary Shelley hides behind the settee.