US President-elect Barack Obama and his family on Thursday will check into Blair House, the historic US presidential guesthouse just across the avenue from the White House.

The Obamas, who spent about 10 days in a posh hotel just a steps away as their girls settled into new schools, could not check into Blair House until all of President George W Bush's scheduled guests, including former Australian prime minister John Howard, had come and gone.

Known as Blair House for the family of Francis Preston Blair who moved into the home in 1837 -- the original core of which was built in 1824 -- the guesthouse now comprises four stately town homes connected internally.

The complex overlooks the White House, but actually overshadows it in terms of size: it has a generous 119 rooms and total area of 6,503 square meters.

If the girls go missing at playtime, someone might check in Blair House's "14 guest bedrooms, eight staff bedrooms, 35 bathrooms, four dining rooms, kitchen facilities, laundry and dry cleaning facilities, an exercise room, a flower shop, and a fully equipped hair salon," the house's website boasts of its amenities.

"Blair House strives to be comfortable, discreet and secure, and to provide any service that a visiting dignitary might require," it notes, with some photos to assure demanding heads of state and government.

Francis Preston Blair was publisher of the Globe newspaper and "lived a highly political life, and a number of presidents including Andrew Jackson, Martin Van Buren and Abraham Lincoln found his advice, counsel and insight very valuable," the site explains.