What are the most sane ways of visualising the structure of software?

Let's just open with some Brent Victor stuff as an entré

Learnable Programming

ChrisKnott/Algojammer

With a less shithouse version of UML?

The C4 model for visualising software architecture

With sequence diagrams?

Ballerina

Event Modeling: What is it?

Or with graphs?

Nodes - Our Story

Gource - a software version control visualization tool

Luna

Or with marbles?

RxMarbles: Interactive diagrams of Rx Observables

Or with a city metaphor?

Code Is Beautiful!