In the year following the opening of Almack's Club in Pall Mall, Almack had built for him by Robert Mylne, the suite of Assembly Rooms, in King-street, St. James's, which was named after him, "Almack's," and was occasionally called "Willis's Rooms," after the next proprietor. Almack likewise kept the Thatched House Tavern, in St. James's-street.

Almack's was opened Feb. 20, 1765, and was advertised to have been built with hot bricks and boiling water: the ceilings were dripping with wet; but the Duke of Cumberland, the Hero of Culloden, was there. Gilly Williams, a few days after the opening, in a letter to George Selwyn, writes: "There is now opened at Almack's, in three very elegant new-built rooms, a ten-guinea subscription, for which you have a ball and supper once a week, for twelve weeks. You may imagine by the sum the company is chosen; though, refined as it is, it will be scarce able to put out old Soho (Mrs. Cornelys) out of countenance. The men's tickets are not transferable, so, if the ladies do not like us, they have no opportunity of changing us, but must see the same persons for ever." ... "Our female Almack's flourishes beyond description. Almack's Scotch face, in a bag-wig, waiting at supper, would divert you, as would his lady, in a sack, making tea and curtseying to the duchesses."

Five years later, in 1770, Walpole writes to Montagu: "There is a new Institution that begins to make, and if it proceeds, will make a considerable noise. It is a Club of both sexes, to be erected at Almack's, on the model of that of the men of White's. Mrs. Fitzroy, Lady Pembroke, Mrs. Meynell, Lady Molyneux, Miss Pelham, and Miss Lloyd, are the foundresses. I am ashamed to say I am of so young and fashionable society; but as they are people I live with, I choose to be idle rather than morose. I can go to a young supper without forgetting how much sand is run out of the hour-glass."

Mrs. Boscawen tells Mrs. Delany of this Club of lords and ladies who first met at a tavern, but subsequently, to satisfy Lady Pembroke's scruples, in a room at Almack's. "The ladies nominate and choose the gentlemen and vice versÂ, so that no lady can exclude a lady, or gentleman a gentleman." Ladies Rochford, Harrington, and Holderness were black-balled, as was the Duchess of Bedford, who was subsequently admitted! Lord March and Brook Boothby were black-balled by the ladies, to their great astonishment. There was a dinner, then supper at eleven, and, says Mrs. Boscawen, "play will be deep and constant, probably." The frenzy for play was then at its height. "Nothing within my memory comes up to it!" exclaims Mrs. Delany, who attributes it to the prevailing "avarice and extravagance." Some men made profit out of it, like Mr. Thynne, "who has won this year so considerably that he has paid off all his debts, bought a house and furnished it, disposed of his horses, hounds, etc., and struck his name out of all expensive subscriptions. But what a horrid reflection it must be to an honest mind to build his fortune on the ruin of others!"

Almack's large ball-room is about one hundred feet in length, by forty feet in width; it is chastely decorated with gilt columns and pilasters, classic medallions, mirrors, etc., and is lit with gas, in cut-glass lustres. The largest number of persons ever present in this room at one ball was 1700.

The rooms are let for public meetings, dramatic readings, concerts, balls, and occasionally for dinners. Here Mrs. Billington, Mr. Braham, and Signor Naldi, gave concerts, from 1808 to 1810, in rivalry with Madame Catalani, at Hanover-square Rooms; and here Mr. Charles Kemble gave, in 1844, his Readings from Shakspeare.

The Balls at Almack's are managed by a Committee of Ladies of high rank, and the only mode of admission is by vouchers or personal introduction.

Almack's has declined of late years; "a clear proof that the palmy days of exclusiveness are gone by in England; and though it is obviously impossible to prevent any given number of persons from congregating and re-establishing an oligarchy, we are quite sure that the attempt would be ineffectual, and that the sense of their importance would extend little beyond the set."[8] In 1831 was published Almack's, a novel, in which the leaders of fashion were sketched with much freedom, and identified in A Key to Almack's, by Benjamin Disraeli.