A State Room in a large European mansion, is usually one of a suite of very grand rooms which were designed to impress, they were the most luxurious in the house and contained the finest works of art. State rooms are usually only found in the houses of the upper echelons of the aristocracy, those who were likely to entertain a head of state.

Untill the 20th century state rooms in English Country houses were seldom used; being reserved for the use of only the most important house-guests, often a monarch and his consort, or another high ranking member of state, hence the name. They were nearly always of an odd number for the following reason: At the centre of the facade, the largest and most lavish room, (for example at Wilton House the famed Double Cube Room) this was a gathering place for the court of the honoured guest. Leading symmetrically from the centre room on either side were often one or two suites of smaller, but still very grand state rooms, for the sole use of the occupant of the final room at each end of the facade - the state bedroom. The smaller (but still huge) rooms in between would be used for private audiences, a withdrawing room and a dressing room. The smaller rooms were solely part of the bedroom suite and not for public use.

In most English houses today, including the royal palaces, these rooms have usually become a meaningless succession of drawing rooms and the original intention lost, this is certainly true at both Wilton House,Blenheim Palace, and Woburn Abbey. The reason for this is the Edwardian Period, when large house-parties needed a huge collection of salons for playing bridge, dancing, talking and generally amusing themselves, also the occupants of the state bedroom preferred the comfort of a warmer more private room on a quiet floor with an adjoining fully plumbed bathroom.

One board a ship the term 'state room' defines a superior first class cabin.