Parts of the White House's East Wing have been demolished, as construction begins on US President Donald Trump's new ballroom.

Construction crews on Monday tore down massive chunks of a covered entryway and windows in the East Wing, which Trump said is being "fully modernised".

The president previously said that his $250m (£186m) White House ballroom addition would be "near" the existing structure but would not change it.

"It won't interfere with the current building. It won't be. It'll be near it but not touching it - and pays total respect to the existing building, which I'm the biggest fan of," Trump said in July. "It's my favourite. It's my favourite place. I love it."

Trump announced the construction in a social media post, saying "ground has been broken" on the "much-needed" ballroom space.

"For more than 150 years, every President has dreamt about having a Ballroom at the White House to accommodate people for grand parties, State Visits, etc," he wrote.

He said the project is being privately funded by "many generous Patriots". Their identities are unclear still as the White House has not released any names of who might be funding it.

The White House has served as the historic home of the US president for two centuries. The East Wing was constructed in 1902 and was last modified in 1942.

From the south side of the building, the BBC saw several large pieces of construction equipment - some adorned with US flags - near the East Wing.

Trump wrote in his post that the East Wing was "completely separate" from the White House, though it is attached to the main structure.

The covered entryway, which spans much of the East Wing's south side, appeared as though it was being gutted, with concrete debris and metal cables clearly visible from several hundred metres.

Controversy and preserving history

Though the White House and its adjoining parks are administered by the National Park Service (NPS), the president generally has broad powers to make renovations.

Robert K Sutton, former chief historian of the NPS, told the BBC that there is always public concern when the White House goes under construction.

"There has been controversy with anything going on related to the White House pretty much since it was built," he said.

The NPS has guidelines and a rigorous review process for any construction. That includes things like reviewing in-depth plans for a project, vetting the architect and designs and reviewing the costs.

That – he said – hasn't been done here.

"This building is so important. It's considered, I think, to be the most important executive building in the world – yet we just don't know what's happening and I think that's very inappropriate."

Mr Sutton noted that figures for how many people the new ballroom can host have been tossed around, ranging from 600 to more than 900.

The White House has released some information on the project, including drawings that give a sense of its scale and a new interior that includes seating for hundreds and decadent gold chandeliers.

It said that construction would begin in September and Trump had met with those at the National Parks Service and the US Secret Service, among others, about the project.

The Trump administration said it selected Clark Construction to head the project, with McCrery Architects designing it. The White House has said the Secret Service "will provide the necessary security enhancements and modifications" to the building.

"I am honored that President Trump has entrusted me to help bring this beautiful and necessary renovation to The People's House, while preserving the elegance of its classical design and historical importance," McCrery Architects head Jim McCrery said.

Sutton said an extensive review process is typically in place for projects like this to ensure there is functionality to any changes, and that the White House sticks to its iconic appearance - noting these changes will outlive presidents and generations.

He said he worried that this process is being rushed and will be a reflection of Trump and his signature style instead of the country's history.

"It's always been called the People's House," he said.

Trump has installed a number of changes at the White House this year, including re-decorating the Oval Office with a variety of gold decor and paving over the grass in the Rose Garden with concrete to add tables and chairs.

Presidents from Obama to Truman have made changes

The new White House renovation project has also been criticised by the Society of Architectural Historians, an international non-profit group that studies the preservation of historic buildings worldwide.

In a statement last week, the group said it "expresses great concern over the proposed ballroom additions", which it notes, "will be the first major change to its exterior appearance in the last 83 years (since the East Wing in its current form was built in 1942).

"Therefore, such a significant change to a historic building of this import should follow a rigorous and deliberate design and review process."

The American Institute of Architects has also expressed alarm, and called for a transparent review of the project.

But Trump is certainly not the first president to leave his mark on the building.

President Barack Obama, who preceded Trump, had the White House tennis court converted to be able to also host basketball games.

The White House swimming pool was converted to the White House Press Room during Richard Nixon's presidency. Briefings now still regularly take place in the room where presidents once swam laps.

The indoor pool had originally been installed in 1933 for President Franklin D Roosevelt, who swam regularly for exercise due to a polio diagnosis more than a decade earlier.

After it closed, Gerald Ford had an outdoor pool installed in 1975.

Before that, one of the biggest renovations came under Harry Truman, who saw the complete gutting and rebuilding of the White House from 1948 to 1952. Truman was relocated from living at the White House during the extensive project.