What is a columbarium primarily used for?

A columbarium is primarily designed for holding cremated remains. This structure consists of niches or compartments specifically created to safely store urns containing the ashes of deceased individuals. Columbariums provide a respectful and permanent resting place for cremated remains, often allowing for personalization and memorialization by family and friends.

In contrast, burial plots are designated areas in a cemetery for traditional burials, while memorial trees and gravestones serve different functions related to commemoration and memorialization but do not specifically pertain to the internment of cremated remains. Therefore, the primary use of a columbarium is indeed for the containment and display of cremated remains, making the chosen answer the most appropriate.