My D&D group usually plays online, we get together once a year to play in person. For this year’s (in January) I put together a little multi-tiered town square.
Each important location in town had a corresponding index card, when a player wanted to take a look I handed them the card and had them read out the description of what they saw.
Sounds like a fun way to do things with the index cards. Having the buildings be black and white sets a tone really well.
For floors I’ve enjoyed printing a texture and gluing it to some foam board for some quick terrain.