Etheldreda’s celestial ship

Octagon lantern

Lantern exterior

Some time in the seventh century the pious Anglo-Saxon princess Etheldreda fled a forced marriage to an isolated island in the East Anglian fens. Through much of the night she fought demons, but on waking she found a tree had grown and flowered above her, signalling God's intention that she found a monastery on the island, however seemingly inhospitable.

Whatever you make of that story a miracle of a kind did subsequently take place on the Isle of Ely over the following centuries: the construction of - in my experience so far - the most beautiful building in England, Ely Cathedral.

During a holiday last week I was fortunate to be able to visit it again for the first time in many years. I've attended a few design conferences and art exhibitions this year, read my fair share of design books, and seen some fine arts programmes and films. But a trip to Ely has done more than any of that to remind me of what design can be.

The Cathedral presents an extraordinary spectacle from the outside. Set on what seems to be the only hill in the fens it is visible from all directions for miles around, and has come to be known as the 'Ship of the Fens', looming as a massive vessel gliding on the flat horizon. As you approach the structure comes into focus, and the building's huge bulk is seen to consist of layer upon layer of intricate stonework.

Entering the Cathedral opens up another order of experience. England's other great cathedrals, York, Lincoln and Canterbury, are monumental. But Ely, I think, has another quality: a delicate ambience that would seem impossible to conjure from a space constructed from countless tonnes of masonry and ironwork. The space is suffused by a gentle, mellow, dappled, rosy light: there's a feeling of warmth.

Lantern and nave

This unique atmosphere is due in part to the Cathedral's fine stained glass, but primarily to the its most beautiful and unusual element, an Octagon 'lantern' tower that rises at the centre of the church. The lantern was built in the 14th century to replace the original Norman cross tower that collapsed in 1322. The Octagon's huge windows allow light into the building at precisely the point where shadows gather in other cathedrals. As the light streams through the shafts and beams create spectacular multicoloured patterns on the Cathedral walls and floor. There's an Ely Cathedral Flickr group that does more justice to it than the snaps I was able to take with my mobile phone.

The effect is somewhat like standing in a forest glade on a brilliantly sunny day. But this is a supremely ordered space, every inch engineered by design. Each line and pattern in the elaborate ornamentation has its purpose and is in symmetry with its neighbour. The sense is of perfect harmony and balance. To use the vocabulary of 20th century design, it's an ideal example of form and function. That's a term usually applied to stark modernist designs with limited colour palettes, smooth surfaces and few if any decorative elements. But I think it's entirely appropriate to apply it to the Octagon lantern: here the form fulfills its function perfectly: to glorify God, who Ely's master masons saw as the divine architect, the ultimate author of the principles of sacred geometry used to construct the Cathedral.

Ely has forcefully reminded me that it's very easy to apply the principle of form and function too harshly. The temptation is to be too severe, too minimalist, too fearful of ornamentation. I'm enough of a modernist to think that form follows function, particularly in regard to the design of web interfaces, but it is easy to underestimate the extent to which beauty enhances function. Design theorists have a term for that: the Aesthetic-Usability Effect. It's a theory more closely associated with product design than cathedrals, but for me Ely is the most successful illustration of it I've yet seen.

Lady Chapel shadows