Why was the column of trajan built?

The forums in general were built as social and political meeting places. They had shops, banks, schools, libraries, and just really regular stuff you would see in a small town. The Word "Forum" means "Marketplace". The Forums were also used to glorify the names of the rulers so that they could be remembered after the end of their rule. Trajan's Forum - though it was much more grand - was used for that purpose also. In the center of Trajan's Forum was a column that showed the victories over the Dacians.