The skies above Athens turned orange on Tuesday as clouds of dust from the Sahara blew north, casting an eerie glow over the Greek capital’s landmarks.

The phenomenon isn’t new — sandstorms from North Africa have shrouded Britain, Greece and Spain in the past — but the event led to remarkable scenes around the Acropolis and in other parts of Athens.

That’s because the dust cloud was more concentrated than those that have hit Greece in previous episodes, according to Kostas Lagouvardos, research director at the National Observatory of Athens.

“It’s the worst such case in years,” he said.

While the dust had dissipated on Wednesday, the Greek Health Ministry urged people to avoid exercising outdoors and to keep their doors and windows shut.

Here are photos from Athens on Tuesday.