The White House Situation Room, the ultrasecure facility known to West Wing insiders simply as “the whizzer,” has undergone a $50 million renovation, with sophisticated communications equipment and technology to prevent American adversaries from listening in.

To walk into the heart of the refurbished Situation Room, which got its nickname from the acronym WHSR, feels a bit like entering the set of a Hollywood thriller. In the windowless basement, one floor down from the Oval Office, the president’s oversize swivel chair faces three huge screens that he can consult while overseeing covert operations around the world.

“This was enhanced to the highest standard,” said Marc Gustafson, the senior director for the White House Situation Room, who oversaw the renovation. “You constantly enhance to keep up with foreign adversaries.”

During a tour for several journalists on Thursday, a panel built into one wall glowed bright green, with the word “UNCLASSIFIED” and the phrase “MICS OFF,” indicating that the room was not being monitored at that moment. A world clock listed the current times for cities including Tehran and Kyiv. It also listed POTUS, so aides can always know the time wherever the president may be.

The walls, built from sustainably harvested wood, hide what officials say are the most sophisticated technologies in the American arsenal for keeping the room secure. Last upgraded in 2006, the room and the surrounding offices have been closed for a year while contractors gutted the old facility and carried out a complete overhaul.

It was the intelligence arms race that led the president to approve the upgrade. Computer monitors and servers that seemed modern in 2006 — the year before the iPhone was announced — had become old and creaky. The signal-blocking technology was in need of modernizing in the era of high-tech sparring with China and Russia. Even the furniture had become worn from seven-day-a-week use.

(When President Barack Obama wanted to monitor the killing of Osama bin Laden in 2011, Mr. Gustafson said, the main conference room did not have the technology to stream the Defense Department feed, forcing the president and his top aides to watch in a cramped room next door. That has been fixed, he said.)

Movies and spy novels describe the Situation Room as a single place where presidents meet with their aides to make top-secret decisions in a crisis. In fact, it is a warren of rooms that represents what White House officials describe as the most technologically secure spaces in the country.

What had become over the years a slightly grungy workplace now gleams — and smells a bit like a new car, with leather chairs in every room. The reception room feels like entering the lobby of a luxury hotel, with the White House seal etched into a marble slab sourced from a Virginia quarry. Down the hall from the staff entrance is the V.I.P. door, used only by the president and vice president.

“It’s a marriage of the traditional and the modern,” Mr. Gustafson said proudly.

The main conference room is known as the J.F.K. room, in honor of the former president. It was President John F. Kennedy’s staff who decided to build a secure facility under the West Wing after the Cuban missile crisis. Until then, the president did not have a central, secure location for reviewing and discussing classified information.

The small conference room where Mr. Obama watched the bin Laden raid has been torn down. The walls, furniture, lighting and other equipment were saved and will be sent to the Obama Presidential Center. In its place are two small, secure “breakout” rooms for people like the secretary of state, attorney general or secretary of defense to work privately when they come for meetings with the president.

Two other small conference rooms are outfitted much like the J.F.K. room, with similar screens, bug-busting technology and a panel showing those in attendance the classification level of whatever is being discussed. All the rooms have LEDs in the ceiling that can change colors; on Thursday, one of the small conference rooms was bathed in blue light.

Around the corner is a closet just for the official seals, which have magnets so they can be swapped out. There’s one for the president, another for the vice president, and several generic “Office of the President” seals for use when someone like the national security adviser presides in the room.

Down another hall is the nerve center of the Situation Room: the Watch Floor. The largest of rooms, it is outfitted with three rows of desks facing a massive wall of flat screens. During the tour, the screens on the wall and the monitors at the desks were all blank or only showing the seal of the Executive Office of the President.

In normal times, Mr. Gustafson said, the screens would be filled with data, classified and not — video streams, social media, maps of the world and intelligence reports from the C.I.A., the Defense Department and elsewhere in the government. Usually, one TV rotates between major news networks.

At the desks sit 17 officials from agencies around the government; every military branch and spy agency is represented, along with State Department, the Department of Homeland Security and a few others. Day shifts begin at 5 a.m. and end at 5 p.m., when the night crew rotates in.

Those are the people responsible for alerting the president and his top aides to any possible crisis. If North Korea fires a rocket in the middle of the night, it is the Watch Floor that wakes someone up — usually the president’s national security adviser. Mr. Gustafson, who also is wakened, said his sleep got interrupted frequently.

The Watch Floor is also the place that manages the secure calls that flow into and out of the White House. When the president wants to call a world leader, often with little notice, a crew of up to a dozen people from the Watch Floor springs into action, setting up the secure video connections and making sure that both sides of the conversation are in sync.

Mr. Gustafson and his deputy have two offices with glass walls at the back of the Watch Floor, overseeing the operation. In true Hollywood style, though, the glass turns opaque at the flip of a switch — the better to have a discussion without peeping eyes.

During the past year, Mr. Biden and his top aides have been forced into using other secure rooms in the West Wing and facilities in the Eisenhower Executive Office Building, next to the White House. Mr. Biden held his first meeting in the new space on Tuesday, two days before leaving for a foreign trip to India and Vietnam.

Much of the senior staff weighed in on the design of the facility, which retains the dark paneling of the previous one but with sleeker lines and high-tech lighting that make it feel more modern. It was a consensus design, Mr. Gustafson said, without confirming whether Mr. Biden was consulted directly.

In the future, Mr. Gustafson said, a complete, yearlong renovation should not be necessary. The new walls, ceilings and floors are modular and designed to be taken out to allow access to the technology underneath.

“We should not have to do another gut renovation,” he said.