During the dissolution of the monasteries all the monastic institutions in the City were closed including St. Leonards Hospital and in 1539 St. Mary's Abbey. In 1547, fifteen parish churches were closed, reducing their number from forty to twenty-five, a reflection of the decline in the city's population. Despite the English Reformation making the practice of Roman Catholicism illegal, a Catholic Christian community remained in York although this was mainly in secret. Its members included St. Margaret Clitherow who was executed in 1586 for harbouring a priest and Guy Fawkes who tried to blow up the Houses of Parliament in 1605.