The principal city of Morocco, and capital in all but administration, CASABLANCA ( Dar El Baida in its literal Arabic form) is now the largest port of the Maghreb - and busier even than Marseilles, the city on which it was modelled by the French. Its development, from a town of 20,000 in 1906, has been astonishing but it was ruthlessly deliberate. When the French landed their forces here in 1907, and established their Protectorate five years later, Fes was Morocco's commercial centre and Tangier its main port. Had Tangier not been in international hands, this probably would have remained the case. However, the demands of an independent colonial administration forced the French to seek an entirely new base. Casa, at the heart of Maroc Utile , the country's most fertile zone and centre of its mineral deposits, was a natural choice.

Superficially, with a population of over three and a half million, Casa is today much like any other large southern European city: a familiarity which makes it fairly easy to get your bearings and a revelation as you begin to understand something of its life. Arriving here from the south, or even from Fes or Tangier, most of the preconceptions you've been travelling round with will be happily shattered by the city's cosmopolitan beach clubs or by the almost total absence of the veil. But these "European" images shield what is substantially a first-generation city - and one still attracting considerable immigration from the countryside - and perhaps inevitably some of Morocco's most intense social problems.

Alongside its show of wealth and its prestige developments - most notably the vast Mosquée Hassan II , on a promontory looking out to the Atlantic - the city has had since its formation a reputation for extreme poverty, prostitution, crime, social unrest and the bidonvilles (shanty towns) which you will see both sides of the rail track as you approach Casablanca. The bidonville problem resulted partly from the sheer extent of population increases - which exceeded one million in the 1960s - and partly because few of the earlier migrants intended to stay permanently. Most of them sent back their earnings to their families in the country, intending to rejoin them permanently as soon as they had raised sufficient funds for a business at home.

The pattern is now much more towards permanent settlement, and this, together with a strict control of migration and a limited number of self-help programmes, has eased and cleared many of the worst slums. Also, bidonville dwellers have been accorded increasing respect during recent years. They cannot be evicted if they have lived in a property over two years, and after ten years they acquire title to the land and building, which can be used as collateral at the bank for loans. The dread of every bidonville family is to be evicted and put in a high-rise block, which is regarded as the lowest of the low on the housing ladder.

The problem of a concentrated urban poor, however, is more enduring and represents, as it did for the French, an intermittent threat to government stability. Casa, through the 1940s and 1950s, was the main centre of anti-French rioting, and post-independence it was the city's working class which formed the base of Ben Barka's Socialist Party. There have been strikes here sporadically in subsequent decades, and on several occasions, most violently in the food strikes of 1982, they have precipitated rioting. Whether Casa's development can be sustained, and the lot of its new migrants improved, must decide much of Morocco's future