Long before clocks, humans found creative ways to track time. From falling sand to slow burning incense, we tried it all. But it took a daydreaming astronomer and a whole lot of inventors to create the precise devices we rely on today.

Joy Dolo and her co-host Kira set off on a tour of timekeeping with reporter Carla Javier. Smithsonian curator Carlene Stephens joins them for a timely train ride, and shares the story of how railroads led to the creation of one standard time for all.

Plus, we’ll hear about a clock buried deep in a mountainside that’s designed to keep ticking for 10,000 years. You can learn more about the organization behind it, the Long Now Foundation, here.