Construction workers are putting the finishing touches on the the extremely secretive but so far impressive-looking Apple Store inside Grand Central. We stopped by the construction site on Tuesday afternoon, and while we were barely able to peek past the black box that's concealing the construction site, we can confidently report that Apple will be opening the new flagship in the near future, possibly as soon as Black Friday. It will occupy the balcony on the eastern and northeastern portions of the station's Main Concourse and extend at least three stories upwards along the windows, all the way to the 125-foot-tall celestial-themed ceiling. We spoke both to the security guard and foreman, neither of whom would tell us a thing about the store's progress, though they did give us the phone number of Eric Wagner, a senior development manager in Apple's retail division. When we called Wagner, he gave the same response to each and every one of our questions: "I can't say."

Earlier in the day, a construction worker told Mashable's Samantha Murphy that the site still needed a lot of work. "It won't be any time too soon,' he said. "We still have a lot to do, so my guess is that it will be ready in December." However, hidden securely behind a well-guarded façade, there's no telling exactly how much longer New Yorkers will have to wait. Below is a photo of the progress so far taken from the center of the Main Concourse, facing east. 

At the top of the roped-off staircase, an Apple-employed security guard is stationed 24 hours a day, seven days a week to keep tabs not only on the 750,000 or so commuters that pass through the station but also the workers heading in and out. (Each worker must claim a special ID badge when heading into the site and return the badge upon leaving.) Above the bottom row of black plywood, which forms a solid wall complete with locked doors, lightweight black boards are hanging on hooks and obscure what will undoubted be the store's Apple-adorned façade. One could imagine that when Apple is ready to officially announce the store's opening — which they haven't, though all rumors point to Black Friday — construction workers can pull down the boards to reveal something shiny, even it's just a "Coming Soon" sign. Update: Indeed, Apple pulled off the boards to reveal a train station-style ticker sign that reads "Apple Store, Grand Central, Arriving Soon." It also says, "Grab an iPod Touch. You'll Wish Your Commute Was Longer." David Owens-Callan snapped a photo of the vintage-looking sign below. Similarly, thick black curtains span the rails of the balcony and are apparently taped to the wall on either side. No peeking!

Things start looking interesting as you crane your neck upwards. Workers on both a cherry-picker and a scaffolding appeared to be polishing the iconic, seemingly sky high windows that separate the Main Concourse from the bustle of midtown Manhattan, but there's something in between. We spotted workers walking behind the glass along characteristically blue-tinged glass walkways. We counted three levels connecting the space on the south side of the windows to the north side. We got vertigo just imaging walking across the catwalks while shopping for a new iPhone case, but the views must be magnificent. 

Based on the position of the curtain, the main floor of the store wraps around the the escalator that connects Grand Central Station to the Metlife Building. This is the same space once occupied by Charlie Palmer’s Metrazur restaurant, whom Apple paid $5 million to vacate the spot — a seriously amazing, glorified eviction notice if you ask us. According to The Wall Street Journal, Apple will pay the Metropolitan Transit Authority another $1.1 million in annual rent, which is nearly four times the $263,997 that Metrazur paid. In August, a blogger from the Apple fanboy site 9 to 5 Mac snuck into the recently vacated space for a spycam walk-through before construction started.

A month earlier, MTA officials boasted about the upgrades to the station and at a board meeting spoke vaguely about the look of the new store as well as plans to open a Shake Shack in Grand Central. "It maintains Grand Central as the iconic structure and place that it is," said Metro-North Railroad President Howard Permut. Pay Foye, a board member from Suffolk County couldn't help but take a jab at Grand Central's less glamorous crosstown sibling, Penn Station. "I can't imagine why any kid in Westchester would want to do anything other than go into Grand Central and shop at Apple and eat at Shake Shack," said Foye. "It makes the Penn Station customers no longer second-class citizens … It makes them third-class citizens." Especially given the look of these grandiose renderings from the MTA (via CBS New York's Tony Aiello).

In this floor plan of the Main Concourse, you can see the original Metrazur space to the right. The finished store, by comparison, will clock in at 23,000 square feet making New York's fifth Apple store location the largest in the world.