SINGAPORE - Prime Minister Lee Hsien Loong is staying at Washington's Blair House - also known as the President's Guest House - during his six-day official working visit to the US.

In a Facebook post on Sunday (Oct 22) morning, PM Lee described the sight of the Singapore flag flying over the historic property as an uplifting one, adding that it was an honour to stay there.

Here are eight things to know about Blair House, which has been dubbed the "world's most exclusive hotel".

1.Third time staying at Blair House

PM Lee's last stay was during an official visit from July 31 to Aug 5 last year, which coincided with the 50th anniversary of diplomatic relations between Singapore and the US.

Then-US president Barack Obama hosted a state dinner PM Lee's honour at the White House.

Back in April 2013, PM Lee met Secretary of State John Kerry at Blair House, where both men paid tribute to the strong links between Singapore and the US.

Former Singapore prime ministers Lee Kuan Yew and Goh Chok Tong have also stayed at Blair House.

2. It was built in 1824

The former home of the US Army's first surgeon general Dr Joseph Lovell, it gained political significance when circuit court clerk Francis Preston Blair moved in in 1837, with his family.

At the behest of then-president Andrew Jackson, Mr Blair became editor of the Globe, a failing Washington newspaper that he turned into a pro-administration publication.

The Blairs' residence subsequently became known as Blair House.

3. It dwarfs the White House

With more than 120 rooms spanning a total area of 60,600 sq ft, Blair House is bigger than the US President's official residence, which has a floor space of about 55,000 sq ft.

There are 14 guestrooms each with their own bathrooms, three formal dining rooms, two conference rooms, a hot and cold kitchen, a beauty salon, an exercise room and an in-house laundry facility.

It also houses 18 full-time employees.

4. Becoming the president's guest house

The US government purchased the residence in 1942, at the urging of then-president Franklin Roosevelt.

Since then, guests of the president have stayed there.

Previously, they spent a customary night in the White House, before staying at a hotel or embassy for the remainder of their visit.

5. It serves as a site for American diplomacy

According to the Blair House website, the residence is a staging ground for "internationally focused events that help to advance America's relationship with foreign nations".

Important events such as a 2012 summit of the G-8 Foreign Ministers and initiatives for the Washington Diplomatic Corps have been held there.

A typical schedule for Blair House in a calendar year consists of up to 30 visits by foreign leaders, multiple foreign policy-related luncheons, dinners and receptions, as well as countless official meetings.

6. Who can stay there?

Foreign dignitaries who have stayed at Blair House include former British Prime Minister Margaret Thatcher, former French president Charles de Gaulle, Japan's Emperor Akihito, Russian President Vladimir Putin and India's Prime Minister Narendra Modi.

It is also tradition for the outgoing US President to make the residence available to the President-elect in the days before his inauguration.

The family of a deceased former president also use it as a residence, where they receive condolence calls.

7. Blair House is today actually made up of four different houses

On the outside, Blair House retains the unique appearance of the original home and three other town houses: Peter Parker House, 704 Jackson Place - both built in 1960 and acquired by the US government about a decade later - and Lee House - which Mr Blair built in 1859 next to the original for his daughter.

But internally, the four houses have been carefully integrated to form a single complex.

Renovation works in the early 1950s had initially joined the Blair and Lee Houses into a single facility known as the Blair-Lee House, before further renovation in the early 1980s united all four houses.

A connecting structure merges the Blair-Lee House with the other two properties.

8. It was the scene of an assassination attempt

On Nov 1, 1950, two Puerto Rican nationalists, Oscar Collazo and Griselio Torresola, made a brazen attempt on then-president Harry Truman's life at Blair House.

Mr Truman had been using it as a temporary residence while the White House was undergoing extensive reconstruction.

The duo tried to shoot their way into the house from the front door, to bring attention to the Puerto Rican independence movement.

Torresola was killed, and the policeman who killed him later died from his wounds. Collazo, along with three policemen, were injured after a gun battle on the front steps.