Major construction work has closed off most routes to and from the Masjid al-Haram (the Holy Mosque) in Mecca.

Thousands of worshippers are channelled along just two roads on their way to prayer: The broad Ibraheem al-Khaleel Street and the much narrower Hijrah Street. Pilgrims are showered by occasional sparks from an arc welder working on the construction of an overpass. The tight streets give the impression that the city is brimming with visitors even though July is a quiet month, compared with the visitor numbers seen during Ramadan or Hajj.

The atmosphere is made even more claustrophobic by the dozens of street hawkers, sitting on the pavements along the route peddling their wares – from prayer beads to fake handbags – which they carry in bundles wrapped in blankets.

The crush of people is both awe-inspiring and a constant worry to the authorities. Each year Mecca bursts at the seams when more than 2.5 million men and women pour into the city to perform Hajj, the pilgrimage all Muslims are obliged to carry out at least once in their life if their finances and health permit.

It is a unique challenge and one that is only going to get more intense. Real estate consultants, Jones Lang LaSalle expects the number of Hajj pilgrims to increase to about 3.75 million by the end of the decade.

Planning for such a gathering is compounded by the fact that pilgrimage involves the movement of large numbers between several locations around the city.

Overcrowding has had fatal consequences in the past. In 2006, some 300 pilgrims died during a stampede.

Mecca is now undergoing a major regeneration. Development so far has concentrated on the area directly surrounding the Holy Mosque. Just a few hundred metres out and the neighbourhood become disorganised. Scores of buildings are dilapidated, crammed into the narrow streets, which fan out through surrounding hills.

The grandest scheme was expected to be completed in August. The Clock Royal Tower Hotel will stand just shy of 600 metres, making it the second tallest building in the world after Dubai’s 828m Burj Khalifa.

Overlooking the Masjid al-Haram, the tower is part of the seven-tower Abraj al-Bayt complex being developed by the local Kingdom Holding Company. It will cover more than 1.4 million square metres and will comprise 15,000 housing units, ranging from studios to five-bedroom apartments.

Despite its obvious moniker, the locals do not like to call it the Clock Tower, preferring the name Tower 13. The Arabic word for clock – Sa’a – is the same word for ‘The Hour’ or ‘the Day of Judgment’, explains a Saudi contractor.

The building has generated much controversy since impressions were first released. Many view the dramatic rise of Mecca’s skyline with concern. Islam’s holiest city, founded by Abraham and the place of Prophet Muhammad’s birth has undergone a massive transformation in the past few decades.

The towering minarets of the Masjid al-Haram were previously the tallest structures in the city, but the height-cap on buildings was relaxed in 2008.

“The development is absolutely necessary,” says a Palestinian contractor who has worked in the city. “What else can they do? Keep all these slums?”

Mecca’s rugged topography and rapid population growth has not lent itself to easy development. The city is squeezed into the centre of a valley, which has also left it exposed to regular flash-floods. On the wall of one hotel lobby hangs a striking monochrome image of a pilgrim swimming around the Kaaba in the 1940s.

For now though, Mecca is struggling to cope with the redevelopment. Collecting waste has become a major problem for the city and locals report pools of stagnant water and swarms of mosquitoes around the construction sites. “If the construction is to make it easy for pilgrims than they should be focusing on transport in the city instead of building these towers,” says a pilgrim. 

Critics of the regeneration of Mecca question whether the project is really being undertaken with improving the safety of pilgrims in mind or whether the real aim is to cash in on the ancient holy site.

Most of the buildings already bulldozed used to accommodate Malaysian pilgrims; this has left the country with limited lodgings to offer its 26,000 hajj visa holders.

Pilgrims from Africa, the Indian subcontinent and southeast Asia face being priced out of the prime locations just outside the mosque and forced to seek accommodation further out. They say the future for the city is a centre occupied by only those who can afford to stay there.

Conservationists also claim that hundreds of historic buildings have been levelled to make way for high-rise hotels and apartment blocks. The Turkish government appealed unsuccessfully to the Saudi authorities in 2002 to prevent the demolition of an 18th century Ottoman fortress at Ajyad, which overlooks the city. There are few buildings left in Mecca which pre-date that.

That Mecca no longer resembles the city which gave birth to Islam is hardly a debate. But developers, residents and visitors continue to argue over the merits of each new tower rising in this ever changing city. Some of Mecca’s more scholarly residents recall a saying ascribed to Prophet Muhammad, which describes the final signs that ‘The Hour’ is approaching: “The poor, naked and barefoot, the herders of sheep, shall compete in the raising of tall buildings.”

With a sense of foreboding, they say this is more pertinent than ever given the inauguration of the Burj Khalifa in Dubai and the impending completion of Tower 13.