In November 1892 Dorothea Beale purchased Cowley House for £5,000. Originally built in the eighteenth century, Cowley House had been enlarged in the 1860s. St. Hilda's Hall was established there in 1893 and the building became known as Old Hall (now Hall Building). It was extended in 1897 to provide a new dining room and student rooms. A further wing was built in 1909 with a legacy from Miss Beale. A final extension to Old Hall was added in 1935 to provide a new library and further student accommodation; this was called the Burrows Wing in honour of the first two Principals of St Hilda's.
In 1920 St Hilda's acquired Cherwell Hall, a teacher training college on an adjacent site. It was a family house, named Cowley Grange and built on his College's land in the 1870s by Christ Church chemistry tutor Augustus Vernon Harcourt. In the Vernon Harcourts' time the house was smaller. A swing hung from the main stair for the benefit of the ten children, and tea-tray tobogganing down the stairs was enjoyed. As the first member of the University to admit women to his classes (and eventually the father of eight daughters), it is not surprising that Vernon Harcourt was supportive to his new neighbours. On meeting Miss Beale he invited her to lunch immediately and she was sure that he would 'be a valuable adviser'. Her later letters are peppered with comments like 'nothing to be done but by order of Mr Harcourt' and 'perhaps Mr Harcourt would suggest'.
In 1902 this invaluable neighbour left and Cowley Grange passed to the Church Education Corporation, which proposed to run it as a women's teacher training college, called Cherwell Hall. At the time Miss Beale was suffering badly from tonsillitis and quinsy and had been 'really ill', too ill 'to be told of anything so vexatious'. Her secretary expressed the hope that Christ Church would not agree to the scheme. Miss Beale does not seem to have been pleased with the decision to keep her in the dark. When speaking of a later potential purchase she wrote: 'I am glad to know of any sale that takes place, but it is no use to know after - if I had known, I might have bought the house now called Cherwell Hall'.
The lease became available again in 1920, when the Church Education Corporation suddenly decided to sell, leaving the staff and students with scant notice of closure. St Hilda's was briefly in negotiation with Miss Talbot, Principal of Cherwell Hall, for the provision of other accommodation for her abandoned students. One of the local 'well-wishers of Cherwell Hall' was 'convinced that only stern necessity has caused the Church Education Corporation to take the action which has brought about the present situation' but that the Principal 'is brave and resourceful and will make the best of it'. Miss Talbot had only been in post for a year and had, according to Margot Collinson, a St Hilda's student taking the Diploma in Education, 'made a great change in Cherwell Hall. Words fail her to express what she thought of the place when she came'. Whatever necessity had caused the closure it was to the benefit of St Hilda's, and the lease was acquired for £17,500.
Not that the money was raised easily, a loan being necessary to cover the immediate expense. The College had recently launched an appeal to pay for an extension to Hall building, and this was quickly redirected towards the purchase. Supporters were encouraged to hold sales and entertainments ('£20 or £30 can easily be raised in one afternoon'), to send donations, and to purchase debenture stock at 5% interest. Within a year £13,400 had been raised by the stock alone. Provision was also to be made for renewing the lease when it expired in the 1970s, but in 1949 the College was able to purchase it outright from Christ Church and it became known as South Building.
Old Hall and South were separated by Milham Ford School. The School moved to another site in 1938 and after various temporary uses the building became the architecture department of the College of Technology, Art and Commerce in 1945. It was finally acquired by St Hilda's in 1958.
In 1952 a building programme was launched which took over thirty years to complete; many details of the plan were altered, but ultimately the main objectives were all achieved. The first stage included an extension to the kitchen in South building with a block of undergraduate rooms above it, a new lodge by the gates of South and a boiler house. Lodgings for the Principal followed and in 1958 the dining hall was extended. Following the acquisition of Milham Ford and its conversion into undergraduate accommodation a new driveway and Lodge unified the three buildings. A grant from the Wolfson Foundation made it possible to build a new residential block, Wolfson Building, which was opened in 1964. An additional residential block, between South and Wolfson Buildings, was designed by Peter and Alison Smithson and formally opened as Garden Building in 1971.
During the next twenty years smaller scale projects were undertaken within existing space, including a graduate common room adjacent to the Lodge in 1974. The growing need for student accommodation was met by the purchase of houses in east Oxford and the construction of Fulford House, a small block of flats for graduate students.
The Christina Barratt Building was opened in October 2001. The impetus for the building came from a legacy left by Professor Rosalind Hill, a graduate of St. Hilda's. Named in memory of one of her closest friends, it provides undergraduate accommodation.
The most recent addition to the site is the extension to the Library. Opened in 2005, it provides a lift, new reading rooms, extended issue desk, environmentally controlled store for the archives and rare books, and offices for library staff.
The first College Chapel was a room on the top floor of Old Hall, although as early as 1897 the spiritual had to give way before other considerations and the Chapel was partitioned to create an additional student room. By 1921 the Chapel would no longer accommodate all the students and an appeal was sent out in October 1924, stating that 'we are only aspiring to a temporary wooden building, which shall be as pleasant-looking outside and as beautiful inside as we can manage to make it. If it is well-made and of good material, such a building should last from twenty to thirty years'. The pre fabricated 'temporary' Chapel in the garden of South building, dedicated in 1925, was to stand for nearly forty five years. The construction of Garden Building necessitated its removal and a room in Milham Ford became an experimental Chapel in 1969; like the previous 'temporary' chapel this became permanent. It was extended in 1971 and reconstructed with new windows in 1999, the latter project undertaken in memory of Evelyn Fowle.
The Jacqueline Du Pré Music Building was opened in September 1995. Jacqueline Du Pré was an honorary fellow of the College and the Building is a memorial to her. It provides a concert hall, music practice rooms and recording facilities. A glass foyer was added in 2002.