Before starting work on a building, you must first poses an understanding of perspective. Let's start at the very beginning (if you already have a good grasp of how to use perspective to draw buildings, you can skip ahead to step 10 to begin work on the Twin Towers). Let's start with using one point perspective to create cubes. Using a ruler and a 2H or harder pencils, very lightly draw the horizon line (blue line) and the vanishing point (red X).
Next, draw a few squares floating in various places on the page, but not too close the vanishing point.
Draw lines from the vanishing point to the closest corners of each square (red lines). Then close off your cubes by drawing the back line of the cubes (green line), but be sure to stay within the red lines leading to the vanishing point.
Erase your unneeded guidelines leading back to the vanishing point and darken the lines of the cubes. You now have a cube created in one point perspective.
Now let's work on two point perspective. After drawing your horizon line, place two different vanishing points on opposite sides of the horizon line. This time, instead of drawing squares, just draw a few vertical lines floating on the page in various places. These lines will become the front edge of our cubes.
From the tops and bottoms of each line (cube edges), draw lines leading to both vanishing points on the page. It's ok if some of your lines run through each other because they can be erased later.
Now close off the sides of your cube in the same manner as step 3 above. But we are not done, since we still need to draw one more side of each cube.
This is where it gets a tad tricky. To finish off the cubes, we have to draw the third side on all necessary cubes. For any cube floating above the horizon line, we will draw the bottom side of the cube by drawing a lines from the bottom tips of the side edges of the cube leading to the opposite vanishing point. Similarly, for any cube floating beneath the horizon line, we will draw the top side of the cube by drawing a lines from the top tips of the side edges of the cube leading to the opposite vanishing point. Note that any cube who's front edge runs through the horizon line will not require a third edge, as it is hidden from our perspective.
Erase unneeded lines and darken up your cubes if you wish. You now know how to utilize two point perspective, but we also need to learn three point perspective before we can start drawing buildings.
An interesting feature about the Twin Towers to take notice of is the fact that they are not directly side by side. Here is a bird's eye view of the towers in relation to one another.
To begin working on the Twin Towers, we must first mark our horizon line and vanishing points. We will be using two point perspective. Because of the angle we will be working at, you will need a wide sheet of paper in order to mark your vanishing points properly. Since there are two towers, it is important to understand that they to not share the same vanishing points. Each tower has it's own set of vanishing points. In this case, I have marked the vanishing points for 1 World Trade Center in blue, and 2 World Trade Center in green. They are close to one another along the horizon line, but they do not touch.
Now that our horizon and vanishing points are marked, let's first work on creating the basic structure for the North tower, 1 World Trade Center. As we did in step 5 above, mark a vertical line as the nearest edge of tower 1. From the tip of that line, lightly draw two guide lines receding back towards the appropriate vanishing points.
Using your vanishing point guide lines as a reference, close off the top of the tower and then draw in the sides. Butt the vertical lines of the building into the horizon line.
Repeat these steps to create the South Tower (2 World Trade Center), but be sure to use the send pair of vanishing points. You not have the basic structure of the buildings.
Draw the upper levels of tower, which feature the observation decks. Keep an eye on the appropriate vanishing points.
Both towers seemingly split into 3 sections by a series of levels that are of a slightly different color than the rest of the building. Draw these levels in, as it will add more character to the image.
At this time, you can erase many of your unneeded guide lines so as to keep the page as clean as possible before we continue. We will be doing more erasing later on after we ink as well.
Each tower is 110 stories high. At our distance, it is very difficult to draw every level, not to mention the fact that
the human eye can hardly see them at this distance anyways. However, we can at least draw a series of vertical lines to create the illusion of windows.
To finish drawing the towers, add in a few air conditioning units to the rooftop, along with the tall antenna atop the North Tower. The antenna is a key feature of the towers, so don't overlook it.
Although the towers are more or less complete, the image could use more work to make them really come to life. We can add in some landscaping and water in the foreground to really make things more interesting. Sketch a line of trees and shrubs in front of the tower along with the waterfront. You will have to erase some of the work you did at the base of the towers, but that's ok. It'll be worth it. Have fun with the image by inserting a few boats in the water.
Using the 2 point perspective methods above, draw in some surrounding skyscrapers. Make sure to create new vanishing points along the horizon line for each building, just as we did with the Twin Towers. There are a few buildings in front of the towers, so you'll need to erase a little bit more. Draw in as many or as few buildings as you wish.
These surrounding buildings also require windows. Rather than drawing each individual window on every building, use the methods from step 18 by inserting vertical or horizontal lines on many of the buildings to create the illusion of multiple levels.
Finally, using a ruler and a micron marker, carefully ink your image. Be sure not to accidentally ink any remaining guide lines that may be on your page. To make the Twin Towers stand out from the rest, ink them using a slightly thicker
marker than the other buildings. After the ink is totally dry, erase your pencil marks with a kneaded eraser. And you're done! You now know how to draw the Twin Towers.