There can be little question that the tall building presents one of the most difficult challenges to the architect.

All architecture, classical or not, must have some sense of order, and order is much harder to achieve without the straight lines and right angles that have dominated the building art from time immemorial.

Renzo Piano and Richard Rogers's Centre Georges Pompidou of 1971-1977 - the true prototype of the modern museum as popular architectural spectacle - wound up costing so much more than planned that the French government solved the shortfall by cutting support for several regional museums.

During the modern period, the vanguard architect has usually relied on small residential jobs both to supply a steady income and to serve as 'sketches' for ideas that are often later translated to the larger scale of public commissions.

Avant-garde architects have never been able to depend on the support of the establishment, since the customary patrons of this most conservative and slowly moving art form have historically been resistant to innovation and experiment.

As with many other folk beliefs, 'feng-shui' undoubtedly incorporates some scientifically correct observation or received wisdom based on direct experience of natural phenomena; but it needs to be dealt with skeptically as a credible system of thought. Some feng-shui prescriptions can certainly lead to desirable results.

The work that launched Snohetta into the architectural big leagues was their Oslo Opera House, which will certainly rank among the firm's highlights whatever else they may do. Although this is by any measure a triumph of city planning, the building itself is not quite a masterpiece, though very fine indeed.