Perpetually ascending staircase: How can the man go up all the time and come back to the same place over and over?
The red squares are the same color in the upper part and in the lower part of the "X"
The diagonal lines are parallel.
There are no gray spots at the corners of the squares.
The center circles are both the same size.
There are only white circles at the intersections
The background of concentric circles makes the squares appear distorted.
The circles appear to rotate when you move your head closer and further away from the screen while looking at the dot in the center.
There are no curved lines in this figure.