It is an architectural absurdity. Just south of the Grand Mosque in Mecca, the Muslim world’s holiest site, a kitsch rendition of London’s Big Ben is nearing completion. Called the Royal Mecca Clock Tower, it will be one of the tallest buildings in the world, the centerpiece of a complex that is housing a gargantuan shopping mall, an 800-room hotel and a prayer hall for several thousand people. Its muscular form, an unabashed knockoff of the original, blown up to a grotesque scale, will be decorated with Arabic inscriptions and topped by a crescent-shape spire in what feels like a cynical nod to Islam’s architectural past. To make room for it, the Saudi government bulldozed an 18th-century Ottoman fortress and the hill it stood on.

The tower is just one of many construction projects in the very center of Mecca, from train lines to numerous luxury high-rises and hotels and a huge expansion of the Grand Mosque. The historic core of Mecca is being reshaped in ways that many here find appalling, sparking unusually heated criticism of the authoritarian Saudi government.

A landlocked nation of steppes and desert, Mongolia is now known mostly as a country of nomadic herders. But vast and sudden changes could be in the works for the country’s roughly 3 million inhabitants. … Some call it the “Saudi Arabia of Central Asia.” Analysts at Eurasia Capital have predicted the country’s GDP could swell from $5 billion to $30 billion by 2020, based on its mineral resources alone. The pressure on Mongolia—or “Minegolia,” as some investors call it—to develop is intense.

Just off a desert road about an hour’s drive from this port city, an enormous arched gate capped by three domes rises out of the sand like the set for a 1920s silent film fantasy. It is, instead, a fantasy of contemporary urban planning, the site of what one day will be King Abdullah Economic City, a 65-square-mile development at the edge of the Red Sea. With a projected population of two million, the city is a Middle Eastern version of the “special economic zones” that have flourished in places like China.

The city is one of four being laid out on empty desert around this country, all scheduled for completion by 2030. They follow on the heels of the country’s first coeducational university, which opened last year next to the King Abdullah site, and a financial district nearly the size of Lower Manhattan that is rising on the outskirts of the capital, Riyadh.

Architecturally they couldn’t be more dreary and conventional — bloated glass towers encircled by quaint town houses and suburban villas decorated in ersatz historical styles. Their gargantuan scale and tabula rasa approach conjure old-style Modernist planning efforts like the creation of Brasília in the 1950s or the colossal Soviet urban experiments of the 1930s, but these are driven by anxiety over the future, not utopian idealism.

With more than 13 million Saudis — half the population — under 20, the 86-year-old Saudi ruler, King Abdullah, is trying to create more than a million new jobs and 4 million homes within 10 to 15 years. He and his royal clan envision an economy less dependent on oil, run by a new class of doctors, engineers and businessmen who can function in a global marketplace.