Drawing three dimensional objects isn't tricky as long as the vanishing points and horizon are understood. The only really tricky part about creating three dimensional objects is the shading and details. But drawing a 3D object really only comes down to the right measurements.
Draw a horizon line straight across the paper. This will be where the sky and ground meet. Determine your vanishing point, which is where most lines converge on your drawing.
Draw two parallel lines vertically.
Draw two parallel lines horizontally to form a box.
Add a second piece of paper if you want to extend your vanishing point and make your building longer.
Place your pencil on the top corner of the box. Use whichever corner you want the rest of the building to extend from. Using a ruler, draw a line from this point to your vanishing point.
Draw a box on top of your box. Connect opposite corners of the box with lines to form a box.
Use the lines to help guide a half circle within the box. Then draw a line extending from the top of the half circle to your vanishing point.
Add details like windows and a vent. Use the ruler to get each feature proportionate.
Erase all of your guidelines.
Use a protractor if you're having a difficult time getting your angles proportionate