Many families, who choose cremation, wish to have all or a portion of the ashes placed in a permanent memorial. This allows friends and family to have a place to return for memorialization. Many find it an important part of the grieving and healing process. Many wonderful options exist today.
If a family has an existing plot and wishes to bury cremated remains, the urn can be interred there. It is up to the individual cemetery if they allow multiple internments into a single space. If you want to be in the same cemetery as your family but do not wish to be buried, many cemeteries have mausoleums to accommodate cremated remains.
Portions of some cemeteries / memorial parks are designated for cremated remains. Check with the cemetery in which you are interested to find out what special accommodations they make for cremated remains.
A columbarium wall contains recessed spaces specifically designed for urns. They come in a variety of styles and sizes. Some columbariums allow room for personal items to be added along with the urn or have enough space for multiple urns.