There are only so many ways to kill time during a long layover. You might browse the magazines at a Hudson News or take the time to test out a travel pillow or two. If it's a particularly trying travel day, you may want to while away a few hours at an airport bar. But if you’ve killed enough time in enough U.S. airports, you've probably noticed that most of them have chapels tucked into a corner of the terminal. Some of them are simple, some of them are ornate. Some cater specifically to members of one religion while others are interfaith. So where did they come from, and why are they there?

The biggest surprise in answering the latter part of that question might be that airport chapels weren't originally built for airport passengers at all. According to Smithsonian.com, the first U.S. airport chapel opened in 1951 at Boston's Logan International Airport and was specifically created for the airport’s Catholic staff, largely to offer mass services for workers on longer shifts.

Dubbed “Our Lady of the Airways,” Boston's airport chapel concept was quickly embraced by Catholic leaders around the country. In 1955, Our Lady of the Skies Chapel opened at New York City's Idlewild Airport (which was renamed John F. Kennedy International Airport in 1963). Other Catholic chapels followed.

In the 1960s, JFK added both a Protestant chapel and a Jewish synagogue to its terminals. By the 1980s, Protestant chapels had opened in the Atlanta and Dallas airports as well.

Single-faith chapels dissipated for the most part during the 1990s and into the new millennium. In 2008, The Christian Index ran a story about the changing face of on-the-go religious spaces and declared "Single-faith chapels a dying breed at U.S. airports." As interfaith chapels became the new normal, this inclusiveness extended to the chapels' patrons as well. Instead of remaining gathering places for airport employees, the chapels opened their doors to the millions of passengers traveling in and out of their cities each year.

Today, more than half of America's busiest airports feature chapels, the majority of which are interfaith. Most existing chapels are welcoming to people of all faiths and often include multiple religious symbols in the same room. They have become important spaces for meditation and reflection. Many of them still offer worship services for each of their represented practices, including places like the interfaith chapel at Washington Dulles International Airport, which hosts a Catholic mass on Saturday evenings as well as daily Jewish prayer services. Though each airport chapel is unique in design and services, they all endeavor to offer a much-needed spiritual refuge from the hassle of air travel.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.