The Pantheon was a place of public entertainment on the south side of Oxford Street, London, England. It was designed by James Wyatt and opened in 1772. The main rotunda was one of the largest rooms built in England up to that time and had a central dome somewhat reminiscent of the celebrated Pantheon in Rome. It was built as a set of winter assembly rooms and later briefly converted into a theatre. Before being demolished in 1937, it was a bazaar and a wine merchant's show room for over a hundred years. Marks and Spencer's "Oxford Street Pantheon" branch, at 173 Oxford Street now occupies the site.
The Pantheon was promoted by Philip Elias Turst, of whose life very little else is known. In 1769 he inherited a plot of land which had a frontage of 54 feet (16 m) on Oxford Street and contained two houses, behind which there was a large piece of ground enclosed by the gardens of houses in Great Marlborough Street, Poland Street and Oxford Street. He had some connections with fashionable society, including a lady of means named Margaretta Maria Ellice, who was involved in the management of a fashionable set of assembly rooms in Soho Square. Miss Ellice was briefly Turst's main financial backer, and took soundings to ensure that a new place of public entertainment on an ambitious scale for the winter season similar to Ranelagh Gardens for the summer, would be "likely to meet with the Approbation of the Nobility in General". This assurance being forthcoming the scheme went ahead.
After falling out with Miss Ellice, who had initially agreed to buy thirty of the fifty shares in the business for £10,000, but soon withdrew, Turst issued fifty shares at £500 each and found buyers for all of them except one, which he kept for himself. This provided a budget of £25,000 and work began in mid-1769.
Turst soon found himself in legal conflict, not only with Miss Ellice, but also with some of his new investors, as the budget was exceeded, but in January 1772 the Pantheon was completed. The architect chosen for the job was James Wyatt. He was to become one of the most prominent British architects of his generation, but at that time he was unknown and aged just twenty-two or twenty-three. He appears to have had some sort of indirect connection with Turst, perhaps through his older brother Samuel, who was to be the main contractor for the project.