"He who builds a mosque in the way of Allah, God will build a house for him in paradise." So said Abu Bakr, the first Islamic caliph, and his words have been followed ever since. Throughout the history of Islam mosques have provided the faith with its religious, cultural and communal focus.
They act not only as places of worship but also as schools, community centres, charitable foundations and even (in days past) hospitals and law courts. They are places in which worldly divisions of class, wealth, status and ethnicity vanish, with all becoming equal in the sight of god.
Most mosques around the world are off-limits to non-believers, reinforcing stereotypes and encouraging skeptics to label them as hives of Islamist extremism. Fortunately many of Islam's largest, loveliest and most historic shrines are freely open to all, not only allowing visitors to experience some of the planet's most spectacular buildings, but also to glimpse something of the religious and cultural life of these remarkable monuments to the world's most misunderstood faith.
Few who visit, however, pass up the chance to explore the city's landmark Hassan II Mosque. Completed in 1993, the mosque stands on an oceanfront promontory, its enormous minaret (the world's tallest, at 210m) soaring above the coast like an enormous Islamic lighthouse, while the cavernous interior glows with the magical colours of blue marble mosaics, lustrous tilework and enormous pendant chandeliers.
The square is home to not one but two of the planet's most stunning mosques, the Shah and the Jameh (Masjed-e Jameh) mosques. The Jameh Mosque is the larger and the older of the two, dating back to pre-Islamic Zoroastrian times and has been rebuilt continuously over the centuries to produce the stunning complex you see today, with three stupendously huge, blue-tiled porticoes rising around a vast courtyard, and mirror-perfect reflections in the ablutions pool between.
Perhaps not surprisingly, Abu Dhabi's shiny new mega-mosque boasts its own string of record-breaking attractions: the world's largest carpet lives here, along with the planet's largest marble mosaic. Although it's the serene beauty of the overall conception, with vast expanses of lustrous marble and myriad dazzling domes shining snowy white in the fierce Gulf sunlight, which really lingers in the memory.
A miniature Renaissance cathedral was unceremoniously shoehorned into the heart of the building during the sixteenth century, although this does little to mask the building's Islamic, quintessentially Moorish character, with its endless rows of jasper, onyx and marble pillars – "like palm trees in the oases of Syria" as one visitor described it – with red-and-white horseshoe arches and a dazzling mihrab.
Opposition to the "mosquestrosity" (as its critics dubbed it) was considerable, but supporters hope that the building will provide a valuable symbol of religious tolerance and cultural diversity to the country at large – not least to the current incumbent of the White House, just 21km down the road.