While staff members at the 263-room Trump International Hotel planned little hoopla for what they described as a "soft opening," about 40 protesters opposed to the New York real estate developer's presidential run gathered outside. The opening came eight weeks before the Nov. 8 election.
"It kind of fits his personality that he finds a way to be on Pennsylvania Avenue, one way or another," said protester Judy Byron, 70, a Washington artist.
The hotel, which includes a $20,000-a-night suite, is less than a mile (km) down Pennsylvania Avenue from the White House. The hotel is housed in Washington's third-tallest building, the 1899 Old Post Office, built in the Romanesque Revival architectural style.
Trump said on Twitter he had stopped by the property "to thank all of the tremendous men & women for their hard work!"
The protesters criticized some of Trump's positions, including a promise to build a wall along the Mexican border to block illegal immigrants. Protest organizer Andrew Castro of Baltimore said: "We're out here building a wall against racism."
Dozens of people filtered in and out on Monday afternoon, some to gawk and others pausing for a drink at the hotel's bar.
On his way in, Ric Hedlund, who works in port development, said he had been impressed by the renovations of a building that he said was previously "a dump."
"I'm going in to drink Trump wine," said Hedlund, who added he also supported Trump as a candidate.
Trump's daughter Ivanka, who helped negotiate the 60-year lease with the U.S. government and oversaw the building's revamp and design, said the project had come in a year ahead of schedule and under budget.
"We have really positioned this hotel to not only be the finest hotel in D.C. but in the country," she said in a telephone interview.
A grand-opening ceremony is planned for next month.
Trump attended the 2014 groundbreaking for the renovations alongside local Democratic officials before launching his presidential campaign last year.
While Trump's name is hard to escape in his native New York, where it adorns structures including the Trump Tower as well as a Bronx golf course, the hotel marks his most visible presence in Washington.
His comments describing some Mexican immigrants as criminals prompted celebrity chefs Jose Andres and Geoffrey Zakarian to pull out of the project. Trump has sued them.