thousands of churches nationwide. The Church of England has some 16,000 church buildings, in 13,000 parishes covering the whole of England, as well as 43 cathedrals. Together they form a unique collection of buildings; between 12,000 and 13,000 churches are listed, i.e. are recognised by the government as being of exceptional historic or architectural importance. About 45% of all Grade I buildings in England are churches. Though first and foremost a place of worship, churches are also often the oldest building in a settlement still in continual use. Even in industrial or 20th century settlements, they are a focus. Problems at maintaining economic self-sufficiency Many churches and cathedrals particularly are the largest, most architecturally complex, most archaeologically sensitive and most visited building in their village, town or city. As current congregation numbers stand at relatively low levels and as maintenance bills increase as the buildings grow older, many of these churches cannot maintain economic self-sufficiency but their historical and architectural importance make it difficult to sell them. In the twenty-first century, cathedrals and other famous churches have met some of their maintenance costs with grants from organisations such as English Heritage, but congregations and local fundraisers must pay the entire bill for most small parish churches. Ancillary buildings In addition to consecrated buildings, the Church of England also controls numerous ancillary buildings attached to or associated with churches, including a good deal of clergy housing. As well as vicarages and rectories, this housing includes residences (often called "palaces") for each of the church's 43 diocesan bishops. In some cases, this name seems entirely apt; buildings such as the Archbishop of Canterbury's Lambeth Palace in London and the Old Palace at Canterbury have truly palatial dimensions, while the Bishop of Durham's Auckland Castle has 50 rooms, a banqueting hall and 30 acres (120,000 m²) of parkland. However, many bishops have found the older palaces inappropriate for today's lifestyles and some "palaces" are ordinary four bedroomed houses. Many dioceses which have retained large palaces now employ part of the space as administrative offices, while the bishops and their families live in a small apartment within the palace. Palaces turned into conference centres In recent years some dioceses have managed to put their palaces' excess space and grandeur to profitable use as conference centres. All three of the more grand bishop's palaces mentioned above Lambeth Palace, the Old Palace and Auckland Castle serve