The Netherland's King Willem-Alexander and Queen Maxima have visited two medical institutions and a high school in Chicago as part of a multiday U.S. trip.

The Dutch royals visited Lurie Medical Research Center on Wednesday to promote a research collaboration between Northwestern University and institutions in the Netherlands.

The king and queen shook hands with professors who'll be part of the program.

They also visited the Rehabilitation Institute of Chicago, to see the work the center is doing in robotics, and paid a visit to Gwendolyn Brooks College Preparatory Academy, where they took part in a picnic and seminars on urban farming.

It's Willem-Alexander's first official U.S. visit since becoming king in 2013. The trip began Monday in Washington with a meeting with President Barack Obama and a stop at Arlington National Cemetery.