I live in Europe now, but before when I was in Canada UBC and SFU would do 'Community roundtable cafe philosophy' and there was often Math and Physics professors there. Here it's all Math professors in the cafes with their own roundtable and it's advertised on the University events page. I believe all these events are sponsored through the University.

Here they mainly talk philosophy and crazy advanced, graduate level mathematics that are way beyond my comprehension and often there are industry programmers, visiting professors on vacation, math self taught geniuses who smoke a pipe with huge unkept beards that look insane, students and even this anarchist group that shows up sometimes to talk game theory.

A few Math dept profs hang out on Sundays here too where all the public chess boards are set up and are fully approachable to answer questions as long as they aren't engrossed in a game.

Clicking on the Events page for the UBC Math dept they always have visiting Math profs give free seminars to anybody who wants to show up, and it's easy to get to the university. Every month at least 5 seminars there's one coming up by a visiting prof from UC Berkeley on Lattice Poisson AKSZ Theory, a bunch of discrete math seminars, and 2 seminars today on chemical distances and shape theorems in percolation models with long-range correlations, and retractions of representation varieties of nilpotent groups.

These guys stick around afterwards and are fully approachable I would talk to them all the time about offtopic theory and went to the student bar with a few of them and other students for a few hours.