Among the cactuses in the desert of Arizona, just outside Phoenix, an extraordinary collection of buildings is emerging that will shape the future of the global economy and the world.
The hum of further construction is creating not just a factory for the world's most advanced semiconductors. Eventually, it will mass produce the most advanced chips in the world. This work is being done in the US for the first time, with the Taiwanese company behind it pledging to spend billions more here in a move aimed at heading off the threat of tariffs on imported chips.
It is, in my view, the most important factory in the world, and it's being built by a company you may not have heard of: TSMC, Taiwan Semiconductor Manufacturing Company. It makes 90% of the world's advanced semiconductors. Until now they were all made on the island of Taiwan, which is 100 miles east of the Chinese mainland. The Apple chip in your iPhone, the Nvidia chips powering your ChatGPT queries, the chips in your laptop or computer network, all are made by TSMC.
Its Arizona facility "Fab 21" is closely guarded. Blank paper or personal devices are not allowed in case designs are leaked. It houses some of the most important intellectual property in the world, and the process to make these chips is one of the most complicated and intensive in global manufacturing.
They're hugely protective of the secrets that lie within. Important customers, such as Apple and Nvidia, trust this company to safeguard their designs for future products.
But after months of asking, TSMC let the BBC in to look at the partial transfer of what some argue is the most critical, expensive, complex and important manufacturing in the world.
The poster child for Trump's policy
President Trump certainly seems to think so. He often mentions the factory in passing. "TSMC is the biggest there is," he has said. "We gradually lost the chip business, and now it's almost exclusively in Taiwan. They stole it from us." This is one of the US president's regular refrains.
TSMC's recent decision to expand its investments in the US by a further $100bn (£75bn) is something Trump attributes to his threats of tariffs on Taiwan and on the global semiconductor business.
The expansion of the Arizona facility, which was announced in March is, he believes, the poster child for his economic policies – in particular the encouragement of foreign companies to relocate factories to the US to avoid hefty tariffs.
China is also watching developments carefully. Taiwan's chip-making prowess has been part of what its government has called its "Silicon Shield", against a much-feared invasion. While the original strategy was to make Taiwan indispensable in this area of critical technology, the pandemic supply chain difficulties changed the calculus because relying on a single country seemed like a greater risk.
China claims the self-ruled Taiwan as its territory but Taiwan sees itself as distinct from the Chinese mainland.
So, many currents of the world economy, frontier technology and geopolitics flow through this one site and within it lies the essential contradiction of Trump's economic and diplomatic policy.
He sees this plant as the exemplar of America First, and the preservation of economic and military superiority over China. Yet the manufacture of these modern miniaturised miracles at the frontier of physics and chemistry inherently relies on a combination of the very best technologies from around the world.
The cleanest environment on Earth
Greg Jackson, one of the facilities managers, takes me around in a golf buggy. The factories are almost a carbon copy of the TSMC spaces in Taiwan, where he trained. "I would say these facilities are probably some of the most advanced and complicated in the world," he says.
"It's quite the dichotomy. You've got really, really small chips with really small structures, and it takes this massive facility with all the infrastructure to be able to make them… Just the sheer complexity, the amount of systems that it takes, is staggering."
Inside the "Gowning Building", workers dress in protective clothing before crossing a bridge that is supposed to create the cleanest environment on Earth, in order to protect the production of these extraordinary microscopic transistors that create the microchips underpinning everything.
Konstantinos Ninios, an engineer, shows me some of the very first productions from TSMC Arizona: a silicon wafer with what is known as "4 nanometre chips".
"This is the most advanced wafer in the US right now," he explains. "[It] contains about 10 to 14 trillion transistors… The whole process is 3,000 to 4,000 steps."
If you could somehow shrink your body to the same scale and get inside the wafer, he says that the many different layers would look like very tall streets and skyscrapers.
Manufacturing manipulation of atoms
TSMC was founded at the behest of the Taiwanese government in 1987, when chip executive Morris Chang was directed to start the business. The model was to become a dedicated foundry for microchips, manufacturing other companies' designs. It became wildly successful.
Driving the advancement of the technology is the miniaturisation of the smallest feature on chips. Their size is measured these days in billionths of a metre or nanometres. This progress has enabled mobile phones to become smartphones, and is now setting the pace for the mass deployment of artificial intelligence.
It requires incredible complexity and expense through the use of "extreme ultraviolet (UV) light". This is used to etch the intricate building blocks of our modern existence in a process called "lithography".