Mansion House - Mansion House Street, London, UK - Literary Sites on Waymarking.com

The Literature Page website carries the relevant passage from Mark Twain's book "A Connecticut Yankee in King Arthur's Court":

One very curious case came before the king. A young girl, an orphan, who had a considerable estate, married a fine young fellow who had nothing. The girl's property was within a seigniory held by the Church. The bishop of the diocese, an arrogant scion of the great nobility, claimed the girl's estate on the ground that she had married privately, and thus had cheated the Church out of one of its rights as lord of the seigniory--the one heretofore referred to as le droit du seigneur. The penalty of refusal or avoidance was confiscation. The girl's defense was, that the lordship of the seigniory was vested in the bishop, and the particular right here involved was not transferable, but must be exercised by the lord himself or stand vacated; and that an older law, of the Church itself, strictly barred the bishop from exercising it. It was a very odd case, indeed.

It reminded me of something I had read in my youth about the ingenious way in which the aldermen of London raised the money that built the Mansion House. A person who had not taken the Sacrament according to the Anglican rite could not stand as a candidate for sheriff of London. Thus Dissenters were ineligible; they could not run if asked, they could not serve if elected. The aldermen, who without any question were Yankees in disguise, hit upon this neat device: they passed a by-law imposing a fine of L400 upon any one who should refuse to be a candidate for sheriff, and a fine of L600 upon any person who, after being elected sheriff, refused to serve. Then they went to work and elected a lot of Dissenters, one after another, and kept it up until they had collected L15,000 in fines; and there stands the stately Mansion House to this day, to keep the blushing citizen in mind of a long past and lamented day when a band of Yankees slipped into London and played games of the sort that has given their race a unique and shady reputation among all truly good and holy peoples that be in the earth.

The City of London website tells us:

Until the mid-18th century, Lord Mayors used their own houses or livery (Guild) halls for their work as head of the City's governmental, judicial and civic functions.

The idea of creating a permanent residence arose after the Great Fire of 1666 to provide a house for Lord Mayors who did not have their own livery hall. But it was almost three quarters of a century later that the architect and Clerk of the City's Work, George Dance the Elder, was chosen to design and build the Mansion House. The first stone was laid in 1739 but it was not until 1752 that Lord Mayor Sir Crispin Gascoigne was able to take up residence there. Work was completed in 1758.

The Mansion House is literally at the heart of the City, above Bank tube station and on the site of a livestock market over the River Walbrook sharing a five-way junction with Royal Exchange, the Bank of England and Hawksmoor's St Mary Woolnoth. With the exception of Queen Victoria Street, all the streets nearby (Cheapside, Cornhill, Poultry) are Roman.

Imposingly Palladian in style, it is faced by a grand temple portico at the front approached by flights of steps each side. The entertaining rooms were built on the first and second floors. The first floor had a roofless courtyard (later covered to form the Salon, the entertainment space) and the great Egyptian Hall. The second  floor has a ballroom and private apartments of the Lord Mayor and family. The third and fourth floors contain meeting rooms and staff rooms. The cellars have storage space and once held prisoners' cells, reflecting the former use of the Mansion House as the Lord Mayor's Court.

While the Mansion House retains much of its original character, there have been changes. Some fifty years later, two large roof pavilions were found to be unsafe. Dance's son, George Dance the Younger, removed one in 1795. The other was removed in 1846, and at the same time, the main entrance to the house was moved round the side, after various road works narrowed the esplanade up the steps at the front. There were refurbishments in the 1860s, and 1930s, and in 1991-3.

Today the Mansion House is home to a magnificent plate collection and an art collection including sculptures and the 84 Dutch paintings of the Harold Samuel Art Collection.

The building is Grade I listed with the entry at the English Heritage website tellings us:

1739 to 53, by Dance the Elder. Monumental, classical building with rusticated ground storey and order of Corinthian columns and pilasters through 2 main storeys plus attic above entablature. Altered roof storey behind crowning balustrade/parapet. Narrow north front has 8-columned portico with richly carved tympanum to pediment. Balustraded steps at either side (altered in C19). Long returns to east and west relatively plain but for pilastered end pavilions with large, round-arched windows above Venetian openings. Small Doric portico to west at ground floor level, now main entrance. South elevation entirely plain of yellow brick above ground storey. Numerous iron escape staircases. Ground floor windows have decorative C19 iron grilles. Interior has been altered, especially roofing of courtyard, but retains much of its exceptionally rich original decoration. 2 staircases, 2 largest rooms are ballroom to north, and Egyptian hall to south rising through whole height of building. Much C19 sculpture.