Authorities are starting to dismantle barriers and fencing around D.C. now that the inauguration is over. (Matt McClain/The Washington Post)

Officials have begun to dismantle the fortress of fences and barricades that took over downtown Washington for Inauguration Day, but remnants of a heightened security presence will remain in the nation’s capital far beyond the tense transition of power.

Mayor Muriel E. Bowser (D) requested that the D.C. National Guard be on “standby” until Jan. 30 as part of an ongoing effort to present an “enhanced posture to deal with the threat of white extremism” in the city, she said at a news conference Thursday.

D.C’s homeland security director, Chris Rodriguez, added that the city is working with the U.S. Secret Service and the Biden administration to evaluate security tactics and strategies, such as whether all joint sessions of Congress should be designated National Special Security Events.

Much of the armed encampment in downtown Washington, however, will be gone by the end of Sunday. Bowser said National Guard members from out of town would leave the city in waves beginning Thursday. The Secret Service announced that this week’s National Special Security Event, which allows for intensified public safety measures, ended at noon Thursday.

Crews began removing barriers and fencing on major streets at 6 p.m. Wednesday in a process that city officials expect to take about 36 hours. By Thursday morning, nine of the 13 closed Metro stations were open, and the National Park Service had reopened the Lincoln Memorial and walkways along the Reflecting Pool.

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Mike Litterst, spokesman for the Park Service, said the rest of the National Mall will reopen in sections as areas are cleared and determined to be safe. He said the grounds should be open by Monday, when the last of the Biden team’s permits expire.

At dusk Thursday, the Lincoln Memorial was alive with a steady hum of joggers, tourists and locals seeking a place of quiet reflection. One man sat against a century-old pillar with tears in his eyes. A platoon of National Guard members stood beside him and snapped pictures as the glow of the sun fell behind the Washington Monument.

“I feel like my second home is back,” said Jeff Horton, a 53-year-old from Leesburg, Va., who sat alone on the steps of the Lincoln Memorial.

Horton had not spent time in D.C. since he was furloughed from his job at the Omni Shoreham Hotel in March, saying it felt like a sort of darkness had overtaken the city where he used to work. He felt an urge to return to the District for the first time after watching the inauguration on television Wednesday night.

By the time darkness fell Thursday, it was hard to tell that a historic event had taken place near the Lincoln Memorial less than a day earlier. The nearly 200,000 flags planted on grassy lawns were gone, and the 59 pillars of light that lined the Reflecting Pool had vanished. Only armed National Guard troops, white tents and small trucks removing wired objects from the sides of the Reflecting Pool remained.

AJ Naranca, a 27-year-old from New York, walked down the steps of the Lincoln Memorial with an American flag hanging out of his backpack. He said someone dismantling the “field of flags” had given it to him.

“I mean this is amazing,” he said. “I love getting souvenirs, and this is one I’ll keep for the rest of my life.”

The last time Naranca was in D.C. was for a Black Lives Matter protest in August. He came back to watch the inauguration, which he ended up doing on the TV in his hotel room.

“It feels like the energy of the city is different. I know everything is still kind of locked down, but it feels more hopeful,” he said.

As of Thursday, more than 10,000 Guard troops out of nearly 26,000 in D.C. for the inauguration were still on duty, according to a news release from the National Guard. About 7,000 of them are expected to remain through the end of the month.

District leaders hope rolling reopenings will mark a new beginning for the city and encourage people to return to downtown, where businesses already gutted by the pandemic experienced even more crippling losses since the Jan. 6 attempted insurrection at the U.S. Capitol. D.C. Police Chief Robert J. Contee III urged business owners to take down plywood from their storefronts, saying Thursday that “as we break down these barriers, these fences, the cinder-block barriers, we are asking that everyone just join in with us to include the business community in removing some of these boards.”

The city’s ban on indoor dining lifts Friday, when restaurants will be able to return to 25 percent indoor capacity.

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Regional focus on rebounding from compounding public health and safety crises follows a relatively quiet Inauguration Day, which officials widely consider to be a success following the calamity at the Capitol on Jan. 6. The D.C. mayor’s office said police in the District and federal law enforcement agencies made 16 arrests from Saturday through the inauguration on Wednesday.

At least seven of those arrests involved illegal firearms, and one was of a person who reportedly impersonated a police officer at a checkpoint near the Capitol.

Authorities have said one of the people arrested was from Virginia and had pulled up to a checkpoint Saturday with a firearm and more than 500 rounds of ammunition. The man said he was working for a private security company and had forgotten he had the firearm in his vehicle. He denied having more than 500 rounds of ammunition.

Another man was arrested Sunday near Union Station and the Capitol after police said a member of the National Guard noticed a flag flying from his vehicle noting “III percent,” an extremist group. Police said the man had a holstered handgun and ammunition in his vehicle.

Police responded to numerous reports of suspicious packages or vehicles and three bomb threats, eight of those incidents on Inauguration Day. One of the bomb threats was reported at the U.S. Supreme Court shortly before 10 a.m. Police said all the reports were unfounded.

In addition, authorities said nine people were taken to hospitals with injuries or illnesses since Saturday, seven of them on Wednesday.