So this is a wall...why did I take this photo?
Oh yes I remember, the even red bricks are the
original wall and 
the random grey bricks are what was used to fill the massive gap.
Or maybe it was the other way around. 
Anyway I believe it shows the different centuries 

This is a marble floor of a person's house in Pompeii
Most of the city was destroyed
 but some of the fine
details are still around