As the number of students kept increasing, it soon become imperative to find more space. At the same time ABAC was trying to obtain full accreditation from Office of the National Education Commission (NEC), the Ministry of University Affairs and the Civil Service Commission.

One condition was to have decent library services. Hence the new project that would accommodate the Office of the President, the office of the Registrar, class-rooms and offices for lecturers. At right angle a two story building would harbor a library below ground level and an assemble hall on the top...It was completed in 1976. Full accreditation had been granted a year before...At that time, the Office of the President was on the second floor. It is now the office of the Vice-President for Academic Affairs. The Faculty Lounge was the Registrar's office. The fifth floor which now houses offices for faculty members soon became a library for magazines, reviews, etc. The opposite room saw the humble beginning of the computer department and computerization at ABAC.

St. Marie’s Square is in front of St. Philip & Bernard Hall (P Building). 
General Characteristics
St. Marie’s Square is an area where a tall pillar monument stands.  At the top of monument is the sculpture figure of St. Marie standing on the earth’s globe.  The monument has a square base. Each side of the square base has the following inscriptions. 

The Clock Tower, also known as “TOWER OF DAVID”, is a large clock tower located between the Assumption 1981 AD. Building and the St. Philip and Bernard at the end of the street.

In 1972, the Assumption School of Business (ASB) that had been going on for three years was fully recognized as an institution of higher learning by the Ministry of Education, under the new name of Assumption Business Administration College (ABAC).

But the new college had to be independent and move away from the ACC Campus. The St. Gabriel Foundation, owners of ABAC, had already a 14-rai plot in the middle of pad-fields, with no trees, no plants and a dirt road to reach it, at the end of Soi Moo Ban Seri. The transfer of ownership was promptly made in order to put up a first five-storey building. Twenty-one meter long poles were supposed to support the whole structure, but when the first one disappeared in the ground after a few strokes, the engineer had to stop the piling. The soil was so soft that it required twenty-four meter long poles...Out of necessity, it was a multipurpose building with the finance department cum bookstore, the registrar's office and the office of the President occupying the ground floor in that order. The actual registrar's office was added much later... 

Ground floor: Office of Financial Management, ABAC Bookstore, Adminission Center

The original master-plan envisions 4 to 5 storey buildings scattered around the campus that would have made of ABAC a concrete jungle. As multi-storied buildings sprung around, the administration though it would be better to do the same, put up one or two buildings more and keep ample space for flowers, trees, and grass. The new headquarters of the Bangkok Bank had just been completed … At a lunch meeting between high ranking officers of the Bank and the top administrators of ABAC, the latter were advised not to exceed ten stories, as beyond, costs would multiply, not add … At that time the students toilets were behind the former shed and further away the servants’ quarters. All had to be pulled down to give way for the new Assumption Building that would be in remembrance of “Ratanakosin 200 years”. Innumerable alterations occurred during the construction. Rev. Br. Martin couldn’t help adding an eleventh floor on the original blue-print. The clock that strikes the hour and the carillon that sings the praises of the Blessed Virgin came straight from Northern Italy and the inventor came to have them fixed.

Ground floor to Fifth floor:  St. Gabriel's Library

A six-storey building located between the R.S. 200 Assumption Building and the Martin de Tour Building, St. Louis Hall (L Building) was initially constructed in October 1995 and completed in 1996.

Martin de Tours Building (built in 1986)

Always in need and in quest of space, ABAC had set a wooden building on a swampy spot beyond the new toilets. It lodged a couple of class-rooms and the College Clinic. Viewed from the pond side, it looked quite happy.

On  the other hand, the Student Affairs Department had no place of its own; the MBA program was expanding and other programs were in the marking; CRIB could hardly breathe in its small quarters, between the Office of the Dean of MBA and the MBA secretariat, than the Continuing Education Program Office. To move CRIB to the fourth floor of the St. Gabriel building meant that the student council and all related activities had to find another place. The wooden building location was the ideal place for all these requirements. Dr. Subin Pinkhayan, Minister of University Affairs, presided over the opening in February 1987 and praised the idea of putting up the building to serve the students only.

A venue for activities and recreation of instructors, students and staff of the university, Dr. Choop Plaza was built in 1982 as a memorial to Professor Dr. Choop Kanchanapakorn, a former rector (which was called “director” at that time), the 3rd one of Assumption University.

The Sala is in the Thai architectural style called the "Jaturamuk" it has, as the etymology of the Thai word implies,  four entrances or four fronts. The northern and southern exposures are identical as are the western and eastern exposures. The design imitates the architectural features of the Royal Pavilion in Ayudthaya, minus the crown or canopy of the Royal Pavilion.

The literal translation of Pratipalai is "Dwelling Place of Light". This is an appropriate name for the Sala as the design creates an atmosphere of peach and harmony and provides an aesthetic inspiration conducive to study and contemplation.

ABAC's policy under the present leadership has been two-pronged; to create an international image among faculty and students and to foster Thai Culture. In a cosy little corner near the pond, the International Center and the Thai Culture Center try in their humble way to promote this policy.

In 1988 Thailand gleefully honored H.M. the king as the longest reigning monarch of the Chakri Dynasty. ABAC decided to join in by putting up something grandiose, a fifteen-storied building that would meet with recent developments. The ground floor, christened Hall of Fame, has been the venue for many seminars already. Under, a modern bookstore cum gift shop welcome customers; the first few floors are for classes, then one can find the Computing Centers, the Faculty of Arts, the Research Center, and a restaurant on the 12th floor. The upper three floors are residing quarters with first class hotel rooms for foreign lecturers and occasional visitors. The majestic golden dome that crowns it can be seen miles around.

From Coronation Hall across the basket-ball courts, a splendid Sala Prathipalai, reminiscence of Bang-Pa-In, sets near the Pond a symbol of peace and quietness, an invitation to prayer.

A 4-storey building built in 1991, consisting of offices of advisors, Student Center is the place for various student clubs and ABAC Cafeteria.

This 9-storey Engineering Building was built in 1992, used as classrooms and laboratories for chemistry, biology, electricity, electronics, physics, computers and biotechnology. It is also used as instructors' offices and engineering workshops.