St. Mary's Abbey, also known as the Nunnaminster, was a Benedictine nunnery in Winchester, Hampshire, England. It was founded between 899 and 902 by Alfred the Great's widow Ealhswith, who was described as the 'builder' of the Nunnaminster in the New Minster Liber Vitae. The first buildings were completed by their son, Edward the Elder. Among the house's early members was Edward's daughter Edburga.