American Airlines will begin nonstop flights to Budapest and to Prague in May from Philadelphia. American will also bring back a daily nonstop flight to Zurich, Switzerland, which had ended last year.

The service to three European cities was seen as affirming American's commitment to Philadelphia as a trans-Atlantic gateway.

"By adding these new destinations, American continues its commitment to PHL as our hub carrier," said Philadelphia airport CEO Chellie Cameron. "These new European destinations will enhance the options for passengers."

The flights to Prague, capital of the Czech Republic, and Budapest, capital of Hungary, will be seasonal, starting May 4 and scheduled to Oct. 27, 2018, the company said. The Zurich flight, which will operate year-round, is relocating here from N.Y.'s John F. Kennedy airport, effective March 25.

Budapest and Prague — both designated as World Heritage cities, as is Philadelphia — will be new destinations on American's route map, the airline said. The flights will be available for booking Monday.

In 2015, more than 16,000 travelers visited Philadelphia from the Czech Republic, Hungary, and Switzerland combined, according to the Philadelphia Convention & Visitors Bureau. That number has been projected to grow 4.9 percent by 2020, which was estimated before American's announcement of new international service.

"Summer travel to Europe is very popular," said Vasu Raja, American's vice president of network and schedule planning. "These flights will conveniently connect customers from two very important hubs — Chicago and Philadelphia — to exciting markets across the Atlantic." American also announced a new summer flight to Venice from Chicago, starting May 4.

The Philadelphia-Budapest flight will depart Philadelphia at 6:25 p.m. and arrive in Budapest at 9:25 a.m. the next day. The return flight will leave Budapest at 11:35 a.m., arriving in Philadelphia at 4 p.m.

The Philadelphia-Prague flight will depart PHL at 6:30 p.m., arriving in Prague at 9:05 a.m. the following day.  The flight will leave Prague at 11:30 a.m. and arrive in Philadelphia at 3:10 p.m.

American will operate Boeing 767-300 aircraft on the routes.