They are the same size.

They will never get together.

This structure pushes the limits of your imagination.

Three men have the same height.

Tricky cubes.

Two beams, many problems.

Two faces or a vase?

Two lines are the same size.

Two man are the same heights.

What does the bar go through?

When you concentrate, corners disappear :) (The image is Copyright Archimedes-Lab)

Where are these people walking?

Where is the water flowing to?

Which one is longer? Don't make a rapid decision.

Which vertical lines is longer? Or they equal in length?

White angels or black bats?

Who is going down, who is up?

Woman Cellist.

You are advised not to look at this picture for long.

You are being watched.