ONE of Harvard's finest collections, its most often seen but most frequently overlooked, is the body of artifacts in which the University lives -- its museum of architecture. Le Corbusier should be pleased that his newest construction is also the latest entry in a fairly distinguished lot of buildings.

Extant Harvard structures cover a time of 243 years and include at least one piece from virtually every important period of American architecture. In this respect the University is very fortunate: there are remarkably few communities in the United States with architectural quality and diversity matching Harvard's.

The best and most nearly complete set in the Harvard architecture collection is the earliest, that of the colonial period. The University owns eight 18th century structures, half of them built especially for academic duties and half of them acquired after long service as private Cambridge residences.

Of these earliest buildings, the real masterpieces are Massachusetts Hall, Holden Chapel, and Apthorp House. Massachusetts Hall, one of Harvard's truly prize possessions, is the oldest College building, constructed in 1720. Few University buildings of equal merit have been erected since. The classic simplicity of its Georgian lines, the excellence of its brickwork, and its immaculate proportions are impossible to better. Holden Chapel, designed by an unknown Englishman, is a very beautiful little building, which manages to look modest and aristocratic at the same time. Its symetrical simplicity is much like that of Massachusetts Hall, the only flourish being its ornately carved pediments which bear the arms of Samuel Holden, a London merchant and donor of the chapel. The interior of the building has undergone several thorough remodelings and lacks the elegance of the original plan but the Georgian proportions of the Chapel are still noticeable and still attractive.

The first bit of marked domestic affluence to appear in colonial Cambridge was Apthorp House, a grand scale dwelling of 1760. It was built as a home for East Apthorp, an Anglican missionary, and its haughty grandeur infuriated the Congregationalists who then populated most of Cambridge and all of Harvard. They had worried for some time about the prospects of an Anglican bishopric being established in their midst and concluded that Apthorp's mansion was to be the "Bishop's Palace" and Apthorp the first bishop.

The house was easily imposing enough to induce such speculation. It stood at the top of a crest overlooking the Charles River with a large expanse of ground stretching before it and somehow had a way of appearing inordinately pompous whenever a Congregationalist should happen by. The neat rows of Ionic pilasters and windows, the classical doorway and the stately scale of the house, contributed to its attractiveness. Now the Master's Residence at Adams House, the building has lost its view of the river and most of its ground but its handsome interior and facade remain intact.

The design of Apthorp House was probably the work of Charles Ward Apthorp, the minister's brother and a relatively competent gentleman builders. Like most educated men of his time. Apthorp considered a knowledge of the orders of architecture an essential part of learning and had mastered the subject well. He was part of the tradition of gentleman architects, who provided Harvard with the schemes for all its earliest buildings.

Elmwood, a majestic wooden house which is now the official home of the Dean of the Faculty, is an achievement of another good but unknown 18th century amateur and it is almost as find a place as Apthorp House. Harvard Hall was built in 1766 after plan sketched by Sir Francis Bernard, the colonial governor of Massachusetts which fancied himself a most proper builder. He was rather successful with his Harvard construction which, until it was badly altered in the 19th century, had been a pleasantly attractive edifice; it could be attractive again, and ought to be restored.

Wadsworth House and Hicks House, the other two colonial domestic structures belonging to the University, are typical works of gentlemen designers and are very representative of the 18th century. Only one Harvard building of this period, Hollis Hall, has been attributed to a professional builder and even that is uncertain. Hollis was designed with polish and excellently constructed but still might be the handiwork of a well-versed amateur.

Charles Bulfinch, eventually to become one of America's most honored architects, was a gentleman builder before he was a professional. He came from a respectable Boston family which had cultivated in him an interest in all the proper disciplines and especially in architecture. He attended to this interest as an undergraduate at Harvard, Class of 1781, and on a trip to Europe after leaving college. His eminence as an architect came surprisingly early in his career, due mostly to the greatness of his design for the Massachusetts State House, one of his first commissions.

Bulfinch's work for Harvard included the original plan for arrangement of buildings in the Yard, Stoughton Hall which he designed as a mate for Hollis, and University Hall, one of Bulfinch's best and one of Harvard's best. This is a building which commands the Yard with authority and flair, is dignified and also very handsome.

When University Hall was first erected, a large and ungainly portico was constructed across the front, apparently Harvard's addition to Bulfinch's original plan, but this was later removed and the exterior elevations seem to be now as the architect intended. Gone also is "University Minor," a row of out houses which stood behind the main structure for many years.

The inside of the Chelmsford granite building has been drastically rebuilt on several occasions and only a small part of the original finish remains. The dining rooms and two kitchens included at the start are gone, leaving only the circular ports through which food was once passed from room to room. The one place in the building which still retains a solid Bulfinch flavor is the old second floor chapel, probably Harvard's most impressive room, now the setting for meetings of the Faculty and the Board of Overseers.

It is possible that the University owns a third and "lost" Bulfinch, one of the large number of buildings which were designed by the architect but never credited to him. Fay House at Radcliffe, built during the time when Bulfinch was particularly interested in houses, possesses the characteristics of Bulfinch's style but unfortunately has lost the credentials of its origin.

After Bulfinch, Harvard erected no important buildings until the late 19th century, a time of professional architects and gaudy edifices. Among the most prominent extravaganzas of this time were Matthews, Weld, and Grays in the Yard and Claverly and Randolph on the Gold Coast. The excesses of these combinations of Gothic and Jacobean design, if unpleasant to see, are reminiscent of the age.