First person Functional buildings are all very well, but thank goodness we can still erect structures just to cheer ourselves up.
A few nights ago, I was having a drink in the new Crowne Plaza hotel in Liverpool. Although its architecture is unexciting, it is a useful addition to the city's amenities and provides attractive views of the Pier Head and River Mersey.

Through the sheer plate-glass window, I saw an even newer building, not yet occupied, which was notable for its chic, late 1990s lines. I asked what it was, and was told that it would provide offices for PricewaterhouseCoopers. Good for them.

This is an attractive example of a structure that is intended to have a specific utilitarian use. Such buildings are, of course, essential, but I must admit that I have an even greater, sneaking fondness for buildings that are far from essential but are there just for fun. I saw such a structure a few weeks ago in Cologne, inside the rather dour opera house.

On the first floor, occupying a space that used to be a perambulatory avenue for opera-goers during intervals, there is now a huge, purple tent. The tent houses a satisfactorily gaudy small theatre, in which opera performances are given for children. It is not needed in the way that the Pricewaterhouse building is needed. It is there simply to provide pleasure. Lovely.

Just as Britain is the home of eccentric individuals, so our nation is noted for its architectural follies. All over the country, mainly in the gardens of the landed gentry, there are strange structures, often modelled on buildings in classical Greece, which are there for no purpose whatsoever except to delight the eye, break the monotony or provide places of assignation for illicit lovers. In the strictest sense of the term, they are a waste of money, which could have been spent on all kinds of worthy objectives.

So perverse is human nature that the worthy objectives change with the ages and are sometimes completely forgotten, while the follies survive to give pleasure to the eye, or at any rate arouse a chuckle or a belly-laugh. There are examples abroad as well as in the UK.

Think of the folly in the garden at Salzburg, used as the location for the Sixteen Going on Seventeen number in The Sound of Music, and still mobbed by visitors today. Think of the fountains at Tivoli, outside Rome, which are cheeky enough to play tricks on visitors (who adore being tricked).

I must admit I have a sneaking fondness for buildings that are far from essential but are there just for fun

In London, I regularly encounter an edifice that is being constructed solely to provide pleasure – a structure that can be described as a folly, in the least derogatory sense of the word. As I walk along the South Bank, on my way to the Royal Festival Hall (which is now at last to receive the lottery grant that will bring about its overdue refurbishment), I come upon the huge, circular structure of the British Airways London Eye. At present, it looks like an enormous white wheel flat on its back. Soon, it will be an enormous white wheel raised up in the air.

This wheel, when erect, will be the tallest structure in London open to the public, at 443 ft high. It has a diameter of 403 ft, and will be kept erect by two 198 ft high columns. Mounted on its exterior will be capsules in which passengers can ride and get a 25-mile wide view of London. It will be the world's largest observation wheel.

There will be 32 capsules, each holding up to 25 passengers, who will get a 30-minute ride – that’s 800 people whirling around at one time. The capsules will be so roomy and secure that passengers will be able to walk about inside them.

This structure is a triumph of European co-operation, with different parts made in The Netherlands, the Czech Republic, Germany and Italy. But it has been designed by British architects David Marks and Julia Barfield; the Tussauds organisation (responsible for, among other venues, the delightful tableau interiors in Warwick Castle) will be in charge of it; and, of course, the whole project is possible only because of the imagination and audacity of British Airways (an organisation often maligned, including, sometimes, by me).

I cannot wait to take a spin on the wheel. At present, it is only intended to be temporary, but I hope that Londoners will insist on keeping it as a permanent fixture. Paris is unimaginable without the Eiffel Tower, and that, too, was intended to be temporary.