Do not worry as you can actually do a lot of things to the space available above your sofa. First you can try to create symmetrical decoration by using a mirror and two artworks that you love. This can be done by putting the mirror on the center then the two artworks on each side of the mirror.
Those who want something simple, you can always use one item on that space. However, you need to make sure that the size of the item is as large as the couch that you use. Or you can also use item that slightly shorter in length than the sofa. Various items can be used such as tapestry or some wall art.
If the room is small and you cannot put too much items then you might want to use a big mirror on the wall. Besides using the mirror as decoration but you can actually make the room appear larger when using this method. Find a mirror that has beautiful frame that match with the style of the room you going to decorate.
For more masculine feeling, you can try to use large size map and hang it above the couch. There are various styles that you can find for the sofa, thus you can find a style that might be more suitable with the room. For example, if your room using classic or industrial theme, then you can try to use vintage style sofa. There are various other ways that you can use to properly decorate any space that you have above couch for your inspiration.
image source : pinterest.com