De Vere Grand Connaught Rooms, a historic events and conference venue in central London. It is a mix of grand historic halls, medium and smaller meeting rooms, and a rooftop/penthouse level, all set up as event spaces rather than bedrooms. There are around 37 spaces It can accommodate roughly 650–750 theatre style and up to about 1,500 standing.
 
The Connaught Rooms sit on a site that began life as the Freemasons’ Tavern in the 18th century, with layers of Masonic, sporting and later commercial history—and a fair bit of implied secrecy. 
In 1769 the Premier Grand Lodge of England resolved to create a central hall, and in 1775 they acquired a property on Great Queen Street for this purpose.Architect Thomas Sandby designed a hall in the garden, while the original house became the Freemasons’ Tavern, serving as both social hub and administrative base for the Grand Lodge.
Throughout the 18th and 19th centuries the tavern hosted numerous societies and associations, using its rooms for committee meetings and dinners. A history continued today!
 
Interesting facts...
it was at the Freemasons’ Tavern that representatives of London clubs met in 1863 to form the Football Association and codify association football rules, an event commemorated on a plaque on the Connaught Rooms façade.