"famous London music-hall whose ornate Moorish-style architecture dominated the east side of Leicester Square. It opened on 18 Mar. 1854 under E. T. Smith as the Panopticon, but with little success, and in 1858 was first called the Alhambra (Palace), retaining the name through successive changes of title (Music-Hall, Palace of Varieties, Theatre, etc.). In 1860 extensive alterations were made to the building and a stage was installed so that it could for the first time be used as a music-hall. "

IN: Hartnoll, Phyllis, ed. The concise Oxford companion to the theatre. 1st ed. London: Oxford University Press, 1972.   ISBN 0-19-281102-9. p. 3

The Alhambra is the best example of a building originally created as a place of 'artistic and scientific edification' but soon taken over by the music hall, which thus made its own an architectural style intended for higher things. Conceived in 1850, the year before the Great Exhibition, as the Royal Panopticon of Science and Art, the building appeared in the Illustrated London News of 31 January 1852 in all its Saracenic glory, 'a style which has as yet no perfect exemplification in the metropolis'. The great onion dome, which was never realized, was copied by the architect T. Hayter Lewis from a daguerreotype of a mosque in Cairo.
The Victorians were thoroughly bored by what they considered to be the monotonous, stereotyped architecture of Georgian England, which they found uninformed and parochial, even vulgar. They wanted something far more colourful, an attitude shared by many people today after decades of the Modern Movement. When the Panopticon opened on 18 March 1854 the facade, save for minor changes, was that of the first design, but with the original dome replaced by a low sixteen-sided cone. Inside, a rotunda 97 feet in diameter and in height held two main galleries facing an immense organ, set into its own double-bayed, proscenium-like recess. 

But the Panopticon was not a success; apparently the committee of clerics and businessmen who ran it could not agree. The high-minded Moorish folly was sold up and on 3 April 1858, with E. T. Smith as its new owner, it opened as the Alhambra Palace with Howes and Cushing's American circus. The central fountain gave way to a circus ring; the great organ was sold to St Paul's Cathedral, and Queen Victoria, who had ignored the building in its serious guise, brought her children to the circus. In October 1858, Smith obtained a licence for music and dancing. In 1860 he erected a proscenium frame around the old organ recess, furnished the floor with tables and chairs and renamed it the Royal Alhambra Palace Music Hall. Those who went to the first night gasped in admiration at the more-Moorish-than-ever redecoration: the house was set on its giddy, exotic way. Certainly, there were difficulties. Drinking, dancing and merriment were never viewed favourably by the police and excuses were found for harassment and closure. The tables and chairs were removed in 1871 and the pit was reseated like a normal theatre. The bars, the cause of all the trouble, had formerly commanded a view of the stage; they were 'now to be found in snug nooks and sly corners'. In 1881, the Alhambra was embellished with an enlarged proscenium and with boxes inserted between the balconies. It was then fitted with stepped rows of seats.

On the night of 7 September 1882, fire destroyed everything but the front wall and the internal columns with their pointed horseshoe arches. It was decided to rebuild immediately in the same style but with fireproof materials, and the building reopened on 3 December 1883. By then, the Saracenic medley of the Panopticon had come to be known as Alhambresque. Further partial reconstruction was carried out in 1888, 1892, 1897, 1907 and 1912.

IN:  Glasstone, Victor: Victorian and Edwardian Theatres: An Architectural and Social Survey. Harvard 1975 p. 49-50

The Alhambra Theatre, London, of 1883, was designed by Perry and Read. The style of decoration, and even some of the structure, was taken over from the building previously on the site, the Royal Panopticon by T. Hayter Lewis, which soon became the 'Alhambra Palace.' It used fire-resistant materials and a cantilever system to minimize obstruction by pillars.

The "Odeon Cinema, Leicester Square" was built on the site in 1937.

Authors: Hartnoll Phyllis, Victor Glasstone