BRUSSELS — Americans can’t imagine the Fourth of July without a huge helping of red, white and blue and flag-waving.

KINDERDIJK, The Netherlands — For almost three centuries, the line of 19 windmills towering over the flat polder — lands that have been reclaimed from the sea — east of Rotterdam have symbolized the age-old Dutch fight against flooding. Now the 21st century is posing a new threat to the mills of Kinderdijk and the rest of the Netherlands. Experts are warning that rising sea levels caused by global warming could overwhelm the complex system of ancient dikes and state-of-the-art barriers protecting a nation with 60 percent of its territory below sea level.

BRUSSELS — Rene Magritte, Belgium’s master Surrealist, discovered home movies when he was in his 60s. But when he did get his hands on a camera there was no holding him and his fellow Surrealists back, as they filmed themselves cavorting around the small Brussels town garden with a Prussian helmet, sea shells and a tuba. A cache of these films is among the treasures at Belgium’s new Magritte Museum, which opens in Brussels June 2.