How many people entered tha Capital building on the 6th ? How many had their cell phones on them? How many of them know that cell phone tower data will have their phone position logged, which will lead FBI to owner of phone? Before you ask? Parts of the building is secure . "They're called SCIFs, and they're designed to let members see sensitive information beyond the reach of prying eyes.

They are tucked all across the Capitol complex, unassuming, behind doors numbered just like any other room. They are rarely mentioned in public, and what is viewed inside is spoken of even less.

But unlike many offices, these rooms host entourages of sharply uniformed military or intelligence officials throughout the day. .

They're the Sensitive Compartmented Information Facilities (acronymed SCIFs and pronounced "skiffs") that serve as secure rooms where those with top-secret clearance can view some of the country's most classified information.

Unlike the dimly lit intelligence offices of pop culture, adorned with flashing space-age computer screens, a congressional SCIF more resembles any ordinary room in the Capitol complex, with a wooden boardroom table and pastel painted walls.

"It's just like any other room, but it takes a weight lifter to open the front door," said Rep. Peter King, former chairman of the Homeland Security Committee and a current member of the Intelligence Committee. "It's similar to the Situation Room in the White House. It's austere, but being in there you wouldn't realize you're in a SCIF."

With Congress currently considering legislation dealing with international trade and federal intelligence gathering, the secretive rooms have been mentioned more and more frequently. As both legislative topics are areas of top-secret statecraft, their ins and outs are off limits to the general public—and even members of Congress get only controlled access to their documentation. Rank-and-file lawmakers can request a briefing and, only in a SCIF, read printed copies of the bills. Each SCIF has a personal security attendant ready to usher the member in, but staff without clearance ws circling the white U.S. Capitol building. The illustration's background ittee. "There's a guard out front. You just check your stuff, punch in your code or whatever you use to get in, and you just go in."

The fact that they have to check their phones and are not allowed to take notes has drawn consternation from members who feel the secretive process keeps them from fully understanding and synthesizing the complicated measures. Nonetheless, defenders of the intelligence community said the precautions are necessary to keep enemies from spying.

"The whole purpose is to not let your enemies to get your information," said Rep. Dutch Ruppersberger, the former ranking member of the House Intelligence Committee. "A SCIF is important to protect classified information from getting out. The technology has developed so much today to the point where our enemies, our Russias, our Chinas, can penetrate right through [the wall] if there's no SCIF."

Every committee that handles classified information has a SCIF, including the Homeland Security, Foreign Affairs, and Armed Services committees, as well as the Defense Appropriations Subcommittee. There is also a general-use House SCIF where any member can read some classified information.

There are literally pages of specifications from the Department of Defense and the Director of National Intelligence for what qualifies as a SCIF, and the cost can run from tens of thousands of dollars to, in the most extreme cases, tens of millions. To start, each room can be built only by U.S. citizens working for U.S.-based businesses who must be accredited by the DOD or another security agency.

In its most basic form, like the congressional reading rooms, a SCIF must include sound attenuation in the walls to ensure no passerby can hear what is being discussed inside.

"The walls are constructed and have to meet specific acoustic performance," said Joshua Godknecht of Adamo Construction, a SCIF-building firm. "It has to mitigate conversations. The definition is that normal conversation and normal speaking voices are unintelligible from the outside."

Those rooms would also have thick multilayer walls incorporating expanded metal grids to prevent forced entry, and both the ceilings and floors are made of the same materials.

At its most technical, a SCIF can be an entire building or a section of a building, encased twice over in unobstructed sheet metal through which no hacker can penetrate. These SCIFs are constructed to allow for secure electronic systems to operate inside without fear of being tapped into.

"It's a box in box," said Bruce Paquin, president of SCIF Solutions, a company that builds the facilities across the globe. "Metal on the outside and metal on the inside. You're making a sandwich on the wall."

That is likely the case with the House Intelligence Committee office suite in the Capitol Visitor Center. The committee used to meet in a secretive fourth-floor Capitol room accessible by stair, but after the attacks of 9/11 plans were drawn for a larger office suite in the CVC (which was partly responsible for the cost overruns during the construction of the massive Capitol add-on). But that allows just the kind of isolation the plans were intended to provide."