The next time you're walking around Boston's financial district, look down. You might see a small "X" etched into some of the bricks around the Atlantic Wharf building.

"As you remove the brick you have the bolts right below, and it's a very easy system to hook up," said Bryan Koop, a vice president at real estate management and development company Boston Properties.

The system Koop is talking about might be the simplest flood protection measure you've never heard of. It's called an AquaFence. The bolts under the bricks act as anchors for the fence — a series of black aluminum panels about 4 feet high, protected at the seams by waterproof blue plastic.

The fence isn't up yet, but a team from Boston Properties — the company that owns Atlantic Wharf — could put it in place at the first sign of a big storm.

"It's amazing, as we look down the street here, and we're looking back at the financial district to our right, and to our left is Boston Harbor and we see the Boston Tea Party, so 800 linear feet of fence going up in a matter of a couple hours," Koop said.

The snow is finally melting around us, but with that comes the threat of flooding. There's been major spring flooding in New England six out of the last ten years — an increasing frequency attributed to climate change. The AquaFence flood protection system has caught on since Superstorm Sandy — and it could help protect some of Boston's key buildings.

It costs hundreds of thousands of dollars to install an AquaFence system around a building. Since Superstorm Sandy, many New York companies have made the investment. The number of AquaFences in Manhattan and Brooklyn has gone from zero to 40.

The trend may be spreading in Boston, a city that's also at high risk of damage from rising seas and increasingly frequent storms. Atlantic Wharf's AquaFence is the first here, but the AquaFence company says it's in talks to bring several more to the city. Koop says he's hosted many local companies that've expressed interest.

"If you're a short-term owner, this probably doesn't make sense for you," he said. "But if you're going to own this asset and this special icon building for decades, you think differently."

Koop says Boston Properties knew it had to think differently after Sandy. The company sent a team to New York to find out what flood protection systems worked. Koop says most of the big buildings that survived unscathed used … sandbags.

"Sandbags," he said. "Well, I'm pretty sure those were around when the Romans were building buildings."

They looked for more innovative options. Boston Properties Sustainability Manager Ben Myers says it was slim pickings.

"We did look at one inflatable solution that wasn't as easily deployed and was inflatable, so it could puncture and not work," he said, laughing.

Myers says the AquaFence was an easy choice. It's portable, reusable, easy to assemble, and — in a modular way reminiscent of IKEA furniture — many of its parts are interchangeable. Myers says they're kept in the parking lot under Atlantic Wharf.

"I've heard stories that when Sandy hit New York there were trucks were stopped, material supplies were commandeered for the emergency response," he said. "This is here, it's secure, we're not waiting for sand or supplies to be shipped in from an outside point."

When it's assembled, an AquaFence turns a single building into something like a walled city, with one big difference: the side of the wall facing out — toward the encroaching storm water — is connected to a series of panels that lie on the ground. Atlantic Wharf's property manager, Barrett Cooke, says floodwater is supposed to cover those panels on the ground, weighing them down and strengthening the whole AquaFence.

"We can keep this up piecemeal," Cooke said. "We can keep our entrances open, we can keep our parking garage open, right until the last minute. We actually have portable staircases that would be strategically placed near our entrance points that are means for people to easily walk across it."

A staircase over a fence right on the street may look a little strange. But Myers says Boston is becoming a city that contemplates options formerly considered strange, as business leaders stop reacting to flooding and start preparing for it. Still, he says, the private sector alone can't protect Boston businesses from the repercussions of climate change.

"Everyone needs to play their part, and this is what we're doing, but we expect that the city's going to lead in areas that aren't directly related to our building," he said.

If the city doesn't make sure power and transportation systems are protected from flooding, Myers says, it's not really going to matter if the AquaFence keeps Atlantic Wharf open.