Skyscrapers are the largest handmade objects on Earth. Every piece is put into place by individuals working according to a complicated plan. We all know about the hard-hats, draftsmen and architects. But is there someone else indispensable to the process?

Of course. The Sidewalk Superintendents, those observers who stand across the street and watch the work unfold. A building couldn’t go up without us.

There are several phases in the job of a Sidewalk Super.

The demolition. This is the bittersweet beginning. It’s great to see something bold and big and new, but there’s usually some timid spinster struck down — say, a small brick building alone in a parking lot, the only survivor from the 1920s, that is clawed apart with indolent cruelty. The demolition machinery never seems to enjoy its work. It’s just business.

The moment the demolition starts, you almost feel embarrassed for the old building. It has to suffer this indignity in public; it has to stand there with half its body clawed away, the jaws of a front loader stripping its bricks. The innards are exposed, and they’re ugly — bent rebar, gray planks of concrete, the guts of the ventilating system hanging out. The building stands and takes it until there is nothing left to disassemble. Then it’s gone. Blank slate. Clean table.

The pit. Workers dig down, their machinery perched on piles of dirt; it’s the job of the Sidewalk Super to judge whether the equipment might topple over. (No, looks good.) You’re reminded how it’s mostly dirt under the asphalt of a parking lot. You imagine pipes and conduits and tunnels, the subterranean world of utilities snaking everywhere. But, no, it’s just dirt. And it’s seeing the sun for the first time in decades.

You look for old relics, but this isn’t Europe; there aren’t Roman roads 40 feet down, so you don’t have to worry about calling the antiquarians because an ancient ruin was uncovered.

The foundation. They’ll dig a square hole for the crane, if one’s needed, and chances are you won’t see it arrive. One day, you’ll look up, and it will be towering over the project like a long-billed stork standing on one leg.

You see sprigs of green metal sprout from the tops of the concrete footings, the rebar that strengthens the columns. Take a good look: You’ll never see them again. They’ll be locked away after another pour.

The service core rises, ugly and gray. In a year or so, it will be holding elevators that people in nice clothes will be riding up and down while looking at their phones. But for now, it’s a stumpy thumb.

The frame. The minute the first beams join to form a floor, it’s a building. Up to now the structure has had no relation to the nice picture on the site, but now the picture looks like a promise, not a wish.

Every week, another floor appears. The Empire State Building, 102 floors high, went up at the astonishing rate of 4½ stories per week, but modern buildings seem to take more time. Of course, the ESB had more than 3,000 men working on it, and modern buildings seem to be assembled by about 20 guys, tops.

Surely, there are more, but you don’t see them. Many afternoons you can walk past the construction site at 3:30 and find no one there. Yet the next day, there’s another story. Maybe gremlins come at night. Union gremlins, of course.

The long middle. Once the frame is up and rising, the site settles into a comfortable rhythm — a new floor is added, a floor below is fitted and finished. Up top, a bare concrete platform; down below, the windows are installed. What you might take for granted is something quite remarkable: Everything fits. It all has been calculated with such precision that the building never groans, settles and then pops out every window in a shower of glass.

As you look up at a residential structure where someone will sit watching the sunset or reading a book in a late spring breeze, wondering if the flowers need water, you realize that the space up there in the sky has been uninhabited for the entire life span of the planet. Until they stacked up these floors, no one had ever been there. Now this plot in the sky has been defined, walled off, commodified, sold and occupied by someone on an Ikea sofa pointing a remote at a TV, occasionally looking out the window at a view no one has ever had before.

The topping out. When the last beam on the highest spot is guided into place, it’s accompanied by an evergreen tree. It’s a tradition that dates to the 8th century, when boughs of grain were brought up to bless the completion of Scandinavian structures. Eventually they started using trees, perhaps to draw a parallel between the growth and wintertime persistence of a pine and the growth and permanence of the building.

After the tree goes up, you may lose interest. It’s as tall as it will get. The floors will be sheathed, the lights will go on. The building will look finished, even though inside there’s carpet to lay, wires to thread, stairwell handrails to paint and all the other innumerable details you never see.

Your work here is finished.

If you’ve been away from a city for a while, you’re impressed by the new buildings. You see how they relate to their surroundings, how they added to the skyline. But if you’re a resident who watched them go up, a building’s completion is like meeting an 18-year-old you babysat when they were 3.

I watched you grow up. But, of course, you wouldn’t remember.