Make a copy of our monument layer and drag it to separate document (create one).

Working with shadow in photoshop

There we have it.

Working with shadow in photoshop

We need this to create a real shadow. OF course I've could painted it but it probably took me some time.

Flip the image and rotate it 180. You will get this.

Working with shadow in photoshop

Drag our flipped image. And here we have it. Now transform the
image, using Distort and Skew.

Working with shadow in photoshop

And don't forget the shadow direction.

Working with shadow in photoshop



Working with shadow in photoshop

Fill the layer with color in layer styles menu.

Working with shadow in photoshop

Create an Alpha Channel.

Working with shadow in photoshop