Few people know that the first sessions of the General Assembly of the UN in 1946 were held in a place of worship - Westminster Central Hall. It was part of an ambitious construction programme, initiated by the Wesleyan Methodists, which resulted in Central Halls in most British cities. They were, and in some cases still are, flexible, multi-functional spaces used on a daily basis for a wide range of purposes. They are widely perceived as public space but they are also sacred - camouflaged churches, created as sites for missionary activity and social outreach by a faith which from its origins has challenged the dichotomy between sacred and secular space.They have never been systematically studied - even their number and locations were unknown. This thesis tells their story by presenting them as an undocumented building type of social and cultural significance. It explores the concept of building type and the dimensions of social and cultural analysis that may be explored with the method. The typological approach is then demonstrated with a specific monographic focus on Methodist Central Halls from the 1880s to the present. Using a combination of visual methods, archival research and personal testimony, the analysis offers insights into the many aspects of Methodism through the long twentieth century - the church's spatial distribution, its modes of mission and worship, its cultural identity and its business model. These centrally located assembly halls with their landmark architecture are for many towns still the top venues for meeting and entertainment. The typology of such public sacred spaces is not only a chapter in the history of British cities but provides findings of wide interest for religion and society.