From the Old Bailey Online

Treemap: Offences 1700-99, categories/sub-categories by decades

"A treemap recursively subdivides area into rectangles; the area of any node in the tree corresponds to its value." Based on this example, which relies purely on colour coding for parent categories; I've added tooltips for offence sub-categories (more info here), which helps somewhat. Also omits decades labels if the rectangle is too narrow for text to fit.

click on rectangles to zoom in/out