Ask HN: How would you implement an indoor map system?

Suppose you had the chance to implement it from scratch, frontend + backend. In my case the data is represented as SVG. So my prototype is based on CSS animation/transforms and SVG interactivity. Now, I can pan/zoom, switch between levels(an animation plays that shows them all in perspective), interact with any element with context menus and popup tooltips and whatever. I can click on a room and see the hours and book a spot. It kinda looks like Apple Maps now. The backend systems are based on Haskell and Postgres to store data, because it is part of a larger system, didn't want to extend the tech stack. For some context, the company I work for is transitioning into a new building and my job is to make it as smart as I can, 100% freedom.

What would you do, even without my particular constraint?