If chemistry plays an important part in marriage, this historic venue in Mayfair is a uniquely appropriate place to do the deed: no fewer than 10 chamical elements have been discovered here. When the building reopens in June (after a £ 22m refurbishment), guests will be able to hold ceremonies in the theatre or main library. There is an in-house catering company, Digby Trout, and exclusive use of the rooms is guranteed at weekends.