Trajan was one of the most loved emperors of Rome.  He is very famous for his Trajan's Market (seen above - the semi circular building) - it is the first shopping mall in the world!  It was 3 levels high, indoors mostly, and worked pretty much like a mall of today.  His forum is just in front of it.  He built libraries for the people and gave them many things that had been for the upper classes before.  Trajan's Column sits just to the left of what you see above - it celebrates his victory over Dacia.  Guess they got tired of arches and thought columns might make for a good change!