Treemaps display hierarchical (tree-structured) data as a set of nested rectangles. Each branch of the tree is given a rectangle, which is then tiled with smaller rectangles representing sub-branches. A leaf node's rectangle has an area proportional to a specified dimension of the data.
This Multilevel treemap enables the user to drill down into another level of the data, or to constantly show both levels expanded.
Once the user clicks on any parent section, they can drill down into that subcategory, in this case, the cities in the US:
In the Multilevel view, the Treemap can be constantly expanded.
One can sort the sections, ascending or descending, and determine if the sections are to be colored by category (break by) or by KPI value: