World Landmarks Light Up Blue For Autism Awareness, and It's Amazing — PHOTOS

You may or may not be aware (and if you're not that's sort of the point), but Saturday is World Autism Awareness Day! Designated by the United Nations back in 2007, this is the ninth year that countries around the world have agreed to participate in raising awareness about autism, and the millions of people who live on the spectrum. And with it comes a strikingly visual, evocative ritual that's taken hold every April 2nd: the sight of world landmarks lit up blue for autism awareness.

Causes and awareness-raising campaigns will often tie a particular color to their cause ― you've probably noticed some of the ubiquitous ones, like pink for breast cancer, or red for HIV/AIDS, sometimes expressed in the form of ribbons. And in the case of the Light It Up Blue campaign, some of the most dramatic skylines and iconic structures in the world get a yearly blue makeover.

It's a campaign headed up by Autism Speaks, a leading American autism advocacy organization. It should be noted that they've previously been the subject of controversy within the autism community for their past funding of research into now-debunked links between autism and vaccination (the group stated unequivocally in 2015 that vaccines are safe). That said, as an awareness-raising exercise geared around color-drenched landmarks, it doesn't get much more high-profile than this sort of effort. Here are some of the striking images.

1. Bayterek Tower

The Bayterek observation tower, which was completed back in 1997, looms over Kazakhstan's capital, Astana.

2. The Sydney Opera House

The Sydney Opera House really needs no introduction ― the Australian venue is one of the most iconic buildings on Earth.

3. The Nelson Mandela Bridge

The Nelson Mandela Bridge in Johannesburg commemorates the late South African president and worldwide peace icon, and joined in for autism awareness as well.

4. Shanghai Tower

The Shanghai Tower is one of the tallest buildings on Earth, clocking in at a staggering 2,073 feet.

5. Patuxai

The gorgeous arch at the heart of Laotian capital city of Vientiane, Patuxai got a dim blue glow for the occasion as well.

6. Luxor Temple

The ancient temple in the Egyptian city of Luxor joined in on the act ― it's by far the oldest structure pictured, having been built more than 3000 years ago.

7. Casa De La Ciudad

It doesn't get much more beautiful than the ornate city hall of the Spanish capital of Barcelona.

8. The Empire State Building

There aren't many American skyscrapers that can boast more towering reputations than the Empire State ― although it's far, far from America's tallest building these days, it still looms large in the public consciousness, and it stands out as a bright, blue beacon.

Images: Autism Speaks (9)