Meet the traveling retirees who have spent 3 years living in Airbnbs around the world

Since July 2013, retirees Michael and Debbie Campbell have consecutively lived in 109 different homes around the world, all booked through room and apartment rental service Airbnb.

Later this summer, a visit to Poland will mark country No. 50.

Throughout their Airbnb-hopping adventure, the Campbells have become a poster couple for the Silicon Valley-based travel company. They've visited Airbnb offices in Portland, San Francisco, and Dublin, spoken at a company conference in Paris, and penned a forthcoming manual for Airbnb hosts called "Your Keys Our Home." They've also mastered the skill of traveling on a budget.

Business Insider recently caught up with Michael, 70, and Debbie, 60, over the phone from their Amsterdam Airbnb.

Scroll through to learn more about how they do it, and follow their adventure on their website, Senior Nomads.