You can install a wood picture / crown molding around the upper edges of the room and then you can hang your artwork by fishing line from the molding. This is a technique that is used in art galleries and it is called a picture molding. It is usually hung just below the crown molding, but you can place it where you want it on the wall. Look it up and you will be able to order the molding and the hanging brackets that are used with the molding.

I would use 3 M COMMAND.....Particularly since your art is small! Zero damage: )

http://www.command.com/wps/portal/3M/en_US/NACommand/Command/Smart-Ideas/Picture-Hanging/