Famous landmarks from around the world are turned blue to mark World Autism Awareness Day on Saturday. 

A number of landmarks, both at home and abroad, lit up blue to mark the day in a move from the United Nations designed to open a conversation about autism and raise awareness around it. 

In Ireland, the National Concert Hall and the Department of Education took part, while around the world hundreds of other famous landmarks followed suit. 

The day can be marked by public buildings turning blue, while on a smaller scale people can start initiatives to light their communities up similarly or by wearing blue.