Funds for a State College of Agriculture were appropriated by the Iowa State Legislature in 1858, and the site on Ioway Creek (formerly Squaw Creek) was purchased the following year. In 1861 a model farmhouse was built, followed during 1864–1868 by the construction of a French Second Empire building designed by Charles A. Dunham. This structure (its wings were extended in 1872) was an imposing one, four stories high on a raised basement. Its end pavilion wings were treated as towers, one of which had a picturesque lantern with balcony. The building was added to by Josselyn and Taylor in 1892; it burned in 1900.

The plan of the college campus began to take shape in the late 1860s, and it has on occasion been credited to Frederick Law Olmsted.4 The scheme was in fact developed by the college's president, A. S. Welch,5 who based it on the English Picturesque Garden tradition as espoused in America by both A. J. Downing and Olmsted. The approach was that of creating a great park, dotted here and there by groves of trees and crossed by curvilinear roads; even the tracks of the small railway between the college and Ames proceeded in an undulating line.

Fortunately, this park has essentially remained intact, though of course many buildings have been added, especially in the surrounding area where agricultural lands have given way to sites for new buildings. In 1906 Frederick L. Olmsted, Jr., was consulted about its design, and he did prepare a report, but his involvement with the campus went no further. During 1915 and 1916 the Chicago landscape architect O. C. Simonds was engaged; his work on the campus was followed by that of several members of the college faculty, especially P. H. Elwood.

The post-World War II years produced an extensive program of new buildings, as was generally true for American colleges and universities across the land. These new structures have usually been built at the edge of the campus, creating a somewhat bland effect (here, nature assumes a poor secondary position); but, as noted before, the core of the campus is still an effective expression of the nineteenth century's version of the Picturesque Garden. An impressive element within the campus is the number of examples of sculptures from the 1930s by Christian Petersen, for many years an artist-in-residence at the university. In front of the Student Union is a fountain designed by Petersen, with figures representing the four seasons. Other outdoor works of his are to be found in front of MacKay Hall and between Oak and Elm halls. Among Petersen's most delightful works are the terracotta panels of the Dairy Industry Building, depicting four cows apparently drinking water from the wall fountain and pool. The Dairy Industry Building was designed by Proudfoot, Rawson and Souers in 1927–1928. Petersen's relief sculpture was added in 1934.