Andrew Mason, the founder of Groupon who was fired as its CEO two years ago, has moved on, literally and figuratively.

Mason and his wife left the daily deal site’s home base of Chicago for San Francisco. And he recently launched a new startup: Detour, whose iPhone app sells location-aware walking tours.

For now, Detour is focused on San Francisco, where it offers quirky tours like “The Fisherman’s Fisherman’s Wharf,” which is narrated by a commercial fisherman and explores the fishing industry hidden to most visitors, and “Trash,” which explores the how the city is shaped by its garbage.

After speaking at the Launch tech conference in San Francisco this week, Mason sat down with Rachel Metz, MIT Technology Review’s senior editor for mobile, to discuss the challenges facing a startup that melds location and audio and the lessons from Groupon that he’s applying to Detour.

How are you making Detour stand out from other podcast- and app-based tours?

If you’ve ever used other audio tour apps, or if you’ve gone to a museum, they all have this similar problem: you’re constantly fidgeting with your phone. For the walking-tour apps, you might be looking at a map and clicking on pins on the map and then playing content or something like that. We wanted something where people could just have an experience that feels like you’re there with a member of the community or whoever it is and the technology just melts out of the way. That’s the whole reason you’re out in the world in the first place. So that made it hard for us from a technology perspective, and a content perspective.

You have to figure out pacing, you have to figure out how to write navigation in a way that isn’t confusing. There’s a remarkable number of nonintuitive ways that people can misinterpret directions. For example, if you say, “Pause here for a second,” instead of stopping [their] walking they might pause the Detour.

I tried Detour with the “Beyond the Painted Ladies” tour of San Francisco’s Western Addition neighborhood, initially because my friend Liz Gannes narrated it, but also because I was curious about what you were working on after Groupon. I was impressed with how well the audio matched up with my walking speed—can you explain the GPS-connected technology behind it?

The way Liz’s Detour works, the one you took, is that there are about 50 pins along a path on a map, each one of which has a segment of narration associated with it. And each time you trigger one of those pins, you trigger the narration that moves the story forward, and then it triggers background music and ambience which is all mixed in real time in the app, like in a video-game engine. Just conceptually, there’s a learning curve to understanding how to write in that style, then how to pace things. In the script you’ll put markers or cues for when you want the listener to start walking, and then you know that you have a certain amount of time until they get to the next stop, and you want the pacing to make sense, and then there’s testing around noise levels in the environment that can be confounders.

The technology that we built for groups is if you and I were Detouring together we form a group, and it’s basically using Bluetooth to send signals back and forth to make sure that we’re at the same place. So if you walk into that next pin, it will send a signal to me saying, “Hey, we triggered this clip, start playing this clip.” If I pause, it’ll send a signal to you, pausing your phone, too, so that we’re having the same experience through our headphones and it’s always synched up perfectly.

What are you doing in places where GPS doesn’t work very well?  

We’re launching an architecture tour later this month that’s in a high-rise zone, financial district, in San Francisco. And GPS gets way off in those zones, so we need something that’s a little bit more reliable. We’re setting up iBeacons along the way that will create a better read.

And then we’re using other sensors on the phone. We’ve experimented with the barometer: in particular, we have Detours where people walk up or down to different floors. Triggering on the Z axis ends up not being quite reliable for us yet.

Right now Detour is focused mostly on walking tours in San Francisco, though I know you’re working with WNYC’s RadioLab on a tour set in Austin, Texas. Can you tell me about that?

It’s in the final stages. We were just down there yesterday testing it. It’s about what basically seems to be America’s first serial killer, who struck Austin in 1885. Never solved the crime, but it’s about how that event kind of helped usher Austin into an era of modernity. They didn’t have a proper police force, for example, everybody would just be a part-time sheriff or whatever; they didn’t have the infrastructure to investigate a serial killer like this. And along that dimension and a bunch of others this event kind of helped bring the city out of the Wild West. It’s an interesting investigation into how that transition happens. You go to some of the murder sites, you go to the history archive and you poke in a folder and you can see the actual, physical archival police logs where they were logging the crime scenes and stuff like that.

As you start to branch out, how will you balance the quality of tours with scaling up to more cities and users? For now, at least, it can take months to make just one of these tours.

It’s about going slow before you go fast and making sure you have all the dials turned in and you know how to create great content before you start scaling, because if you don’t have all that stuff dialed in and you’re scaling with the wrong product, then what’s the point of scaling?

It’s like we’re creating a typewriter at the same time we’re creating the book. For this new medium, we’re trying to create these tools that make it intuitive to create location-based content, which has its own set of challenges, both technical and stylistic in nature. There’s a whole new art to writing for place.

Tell me one thing you learned at Groupon that has been helpful at Detour.

I think a lot of the world is focused on this idea that a lot of people are evil, crazy, and stupid, and that’s why they make decisions. And what I’ve found is it’s rarely the case. Usually it’s just something about not having the same context as that person. So it’s made me a more understanding person, someone who’s more willing to give the benefit of the doubt, and I think that applies with Detour [and] what we’re about. It’s really easy to get outraged when you’re sitting in front of your computer and reading something about something stupid that someone did. It’s harder when you’re actually out there, staring face to face with whatever it is that you’re reading about—whatever the content is that you’re consuming.