The question of building timelines came up today from a viewer and also in my teachings as well at Seattle Central College.
This is Part 2 of 3 in this series of creating timelines.
Start with a square. I use MM to create all my shapes so it is super easy to divide them into sections or line things up using math instead of trying to figure out fractions of an inch.
Use the Direct Selection Tool to select the two right point of the box, then use the SHIFT+DOWN ARROW 5 times to move it down.
Select the Reflect tool, click on the newly transformed box and choose vertical reflect and then COPY.
Line up the two shapes together.
Change the color on the right hand box by double clicking on the color picker at the bottom of the tool bar. Then switch the color mode to "B" (brightness)... Hue, Saturation, Brightness... and this allows you to take the slider up and down to make the color lighter or darker without moving off that specific hue.
Duplicate the right box to line up with the left and send to the BACK.
Copy the left box to line up with the right box and send it to the back, then darken both back shapes using the Color Picker Brightness (Darkness) Slider. Now you have a box.
Duplicate the boxes, using the Smart guides to get the distance in between the consistent. Change the colors accordingly to get some nice hue changes.
I added rectangles with rounded ends to staggered sides, using the opposite side color for the fill color of the rounded rectangle. Text is Museo Slab 700 for the numbers and 300 for the text, which is set in 75% gray.
Add icons to the faces. You will need to use the Shear Tool to get the angle just right to match the box face.
The easiest way to get the icons to match the angle is take an icon or type with a flat base. Then select and use the Shear Tool to set the angle.
Select your object with the Selection Tool. Hold OPTION and (in this case) click on the lower left side to "anchor" that point and open the dialog box. If you don't hold OPTION the dialog box wont open, it only sets the point when you click.
Once the base of the icon becomes parallel with the cube face, then you have your shear angle. Remember that number so you can shear all the icons the same way.
Here are some renditions on how to include type if necessary.
I copied the rounded rectangle from the left and put it on the right with a stroke to help create symmetry. These are simple ways to see what options work best.