Yes I will be doing a Conversation with him.  Most of all he is obsessed with design, here is Wikipedia:

Roman Mars is an American radio producer. He is the host and producer of 99% Invisible, a KALW radio show and podcast, and a founder of the podcast collective Radiotopia, ^{which he describes as efforts “to broaden the radio landscape [and] make shows that aren’t bound by conventions” of public radio in the United States. In 2020, he co-authored the New York Times best seller The 99% Invisible City with Kurt Kohlstedt…Mars, with Elizabeth Joh, also hosts the podcast What Roman Mars Can Learn About Con Law.}

His TED talk on city flags is a good introduction to his thought.

So what should I ask him?