Before starting work on a building, you must first poses an understanding of perspective. We are going to be drawing Buckingham Palace using one point perspective, so let's start with using one point perspective to create a few 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. This is the process we shall use to draw the palace.
To draw Buckingham Palace, we first start by inserting the horizon line (blue line), which should be roughly 3/4 of the way down your page. Note: it's best to work on a horizontal sheet of paper because of the width of the structure. Next, insert your vanishing point (red X) directly in the middle of the horizon line. Draw a vertical line through the vanishing point (green line) which will serve as a measurement guide. Remember to draw very lightly so that these lines are easily erasable later on.
Before we begin working on the actual building, it's best to first draw the fence that lines the perimeter, that way we don't have to erase a bunch of stuff later on in order to add the fence at the end. Using the vertical line in the center of the page as your guide, measure equal distances in either direction to mark the edges of the fence. For example, and as seen with the green lines, if you want the fence to be ten inches wide, then measure five inches on the left side of the vertical guide line, and five inches on the right side (you can work with any measurement your prefer). Then draw a base line from edge to edge, as seen with the red line.
The fence is separated with a series of pillars of different sizes. This is where our vanishing point comes in handy. Be sure that each pillar is created in the same manner in which we created the cubes in steps 1-4 above. It's also a good idea to measure the heights and widths of your pillars so that the pillars on the left are exactly the same size as their counterparts on the right. The two pillars in the center are the largest, since they hold the large gate.
The pillars are adorned with decorative statues and lamp posts. Again, make sure that the decorative fixtures mirror each other on both sides of your center guide line. This will be a rule of thumb to remember for the rest of this process, since Buckingham Palace is perfectly symmetrical on both sides when viewing is from straight on.
Now let's draw in the rest of the fence. This part may appear overwhelming at first, but be patient and it will come together nicely. Draw horizontal guide lines across the page (green lines) so you the proper height of the fence and the horizontal bars the cross through it. There are three gates along the face of the fence - a large one in the center and two smaller ones on either end. Each gate features decorative fixtures including the royal coat of arms. Each rod along the length of the fence is topped with a fixture similar to a Fleur de Lis.
We can now being working on the structure of the palace itself. Let's first start by creating the basic rectangular shape of the building, which is almost as wide as the fence. Remember to use your center guide line for accurate measurement.
The face of the building is divided into five sections. The two sections on the end, as well as the section in the middle, have decorative triangular peaks at the rooftop. The section in the middle is considerably larger than the two on the ends.
Parts of the rooftop of the palace are lined with a short, decorative fence. The main level of the palace is separated from ground level by bricks (which we will draw in later). For now, draw two lines across the length of the palace, roughly at the same height as the center gate. Remember to stagger these two lines with the different sections of the building, since the center and outer sections are slightly closer to use than the other two sections. If you look closely at the image, you'll see what I mean.
The center and outer sections feature tall Corinthian columns which hold up a section of the roof. The middle section of the building has six columns, and the outer sections each have four. There are more columns built into the walls of the building, but we will not draw them just yet.
This is a good time to lay down guide lines for the windows. As you will see in the next step, there are two levels of visible windows in the center and outer sections of the palace, whereas the other two sections each have four levels of windows. Lightly draw in a grid such as this one as a guide for you windows.
After your grid is in place, draw in each window as seen here. The windows on the top and bottom level are much smaller than the others. Also notice the decorative frames of the windows of the mid levels.
Add in additional details such as the decorative statues at the peaks of the entrances (which do not have to be perfect because of our distance from the building), add a lip to the trim of the outer edge of the building, and add the trim along the base of the tall windows. Notice that there are two doorways at ground level. Now is also a good time to draw in the remaining columns between each window, but these columns are built into the walls and are more decorative than they are functional.
Draw in the brickwork of the lower level. These can be done fairly quickly and do not have to be perfect, since you cannot see each individual brick from this distance. Drawing sporadic horizontal lines will suffice. Thin them out as they near the fence - you do not want the image to become messy by drawing layers of bricks behind the fence itself. Notice the arched brickwork above the two doorways.
As a final touch before inking, draw in the flag at the peak of the palace.
Now is a great time to ink the image using Micron or Copic markers. Carefully go over your lines using a ruler and be careful not to ink things that should not be inked, such as guide lines or the vanishing point. After everything is inked, erase your pencil marks with a kneaded eraser.
Go in and add some shadows using a marker or India ink. Establish your light source (in this case, the light is coming from the upper right), and shade the opposite side of each pillar and under the edges of the rooftop trim. Also completely fill in each window with black (we will do the window frames in the next section).
As a final step, use white ink or opaque white paint to make any needed corrections. Also paint in the window trim on each window. It is much better to paint in the window trim in this stage, rather than trim to fill in black around each piece of trim in step 20 because doing that can get very messy. And at this point, your image is complete. Congratulations! You now know how to draw Buckingham Palace!