Behind the scenes of Latin America's internet 'brain'
It may be one of central Miami's most recognisable buildings, yet only a few people know what goes on inside the sturdy concrete block with massive spheres on its roof.
The cube is the Network Access Point (NAP) of the Americas, one of the world's largest data centres, which redirects most of the digital information that comes from Latin America.
About 90% of data traffic from Central and South America passes through the south Florida facility before continuing to its final destination.
The NAP is, in short, one of the internet's brains - facilitating people's online activity, according to Douglas Alger, author of The Art of the Data Center.
"If you send an e-mail, download music, do social networking or buy something, the equipment to make it happen is based in a data centre," he tells the BBC.
In his book Mr Alger describes 18 data centres around the world - including NAP - which play an important role in global digital communications.
"Many of them face the outside world, but you also have others that are really private and support the activity being done by specific businesses," he adds.
Security measures are especially strict at the NAP, and it is rare to be granted access.
The six-storey 750,000-square-foot (70,000-square-metre) structure is full of cables and computers.
It may seem daunting but on a tour of the site Ben Stewart, NAP's senior vice-president for facility engineering, offers assurance.
"Many people do not understand what the internet is," he says. "They think it is a very complex thing to understand, but it is very simple."
He likens the operation to an international airport.
Instead of passengers with excess baggage there are e-mails with heavy attachments, instead of aircraft carriers - internet carriers.
Just as airports have security checks, Miami's concrete cube features its own X-ray machines and sniffer dogs as well as internet-based firewalls, intrusion detectors and other protection devices.
That is why carriers and customers as diverse as Subway restaurants, the library of the US Congress and several US government agencies also use the facility owned by Terremark.
As most of their information is sensitive, no cameras or other electronic devices are allowed. Access to the third floor - 125,000 square feet entirely dedicated to US government users - is restricted to US citizens and requires government clearance.
The centre has a team of experts who sit in front of a dozen giant screens, displaying everything from the FBI's most wanted list to the weather forecast and 24-hour news channels.
Their job is to make sure this digital hub is kept safe and operational, no matter where threats might come from.
The heart of the operation is the so-called peering room - an area on the second floor where internet networks are connected, so that each network's customers can exchange information.
About 18 or 19 gigabits per second go through the NAP's peering fabric, says Mr Stewart - the equivalent of about 36,000 songs per second.
The centre, he adds, is "a playground for an engineer".
The NAP, unlike other data centres, rents its equipment and space to private and public customers, so that they can share information between them.
"For our customers, the main attraction is primarily up time," he explains.
"If you are an internet company, if you have got a store front or you are streaming video, you need to be in a facility that is not going to go down."
To prevent any service interruptions, the walls have 7in (18cm) thick, steel-reinforced concrete exterior panels; the building has no windows, and it is located in one of the highest parts of Miami.
What's more, the satellite dishes on the roof are covered, so no-one can easily determine which way they are pointing.
But what if a devastating weather came to south Florida, such as Hurricane Andrew, which wrought unprecedented havoc in 1992? Would the internet crash in Latin America?
Mr Stewart says it would not because the internet is "self-healing".
According to the engineer, if NAP stopped working, it would also stop sending the signals that indicate it is receiving information. Routers would therefore stop sending data via that path and would seek a different one.
Users might feel that their information took longer than normal because it would have to take alternative routes, but it would eventually reach its destination.
This ensures that "internet communications never fail, even if NAP Miami crashes - which won't happen," he assures.