Whether you were stuck in downtown traffic yesterday morning – or had a birds-eye view from your office – you couldn’t help but notice it.

An ominous black plume of smoke rising from the vicinity of the National Mall, which soon towered over even the Washington Monument.

A terrorist attack? A rogue firecracker from yesterday’s Chinatown parade? A Superbowl barbecue gone awry?

The culprit was actually a small fire on the grounds of the Smithsonian’s National Museum of Natural History.

According to the Washington Post, the fire broke out early Monday morning in a building housing the museum’s heating and air conditioning equipment.

It was put out rather quickly with no injuries, but the after-effects were felt for hours to come, in the form of snarled traffic and a gray haze over the city.

Luckily there was no damage to the Natural History building, which is commemorating its centennial, and recently

overtook the National Air and Space Museum as Washington’s most visited museum.

Although maybe someone should check to make sure the Hope Diamond is still there.

Incidentally, if it hasn’t been heisted, it’s worth checking out – even if you’ve seen it before.

It’s been temporarily fitted with a stylish new setting chosen by the public to mark the fiftieth anniversary of its gifting to the Smithsonian.

The Smithsonian estimates that more than 100 million people have seen it since the donation, making the Hope Diamond the most popular museum object in Washington, and perhaps the world.

No haze there, just 45.52 carats of clear, blue perfection.

As of yet, no one is blaming the fire on a jewel thief’s diversion – or the misfortune that has famously followed the Hope Diamond throughout its history.

But stranger things have happened in the District…