The diaries detail the day to day events in Fred Willson's life. The entries contain information on local, regional, national and international events as well as mundane details such as doctor appointments, car repairs, and business dealings. Nearly every entry contains information on the weather and Willson's daily routine. Major events in Willson's life are noted including his son Lester's first steps, his marriage and the death of his father. There are multiple entries referring to meetings with prominent MSU faculty and past presidents. Local events such as the Bozeman Sweet Pea Carnival, theatrical showings and city developments are often noted. Comments on happenings of the nation are regularly mentioned, including an entry on Willson shaking the hand of President Cleveland on the day Montana entered the union as the 41st state. The 1904-1905 and 1905-1906 diaries detail Willson's nearly sixteen-month long trip to Europe. These two diaries note his impressions of the countries he visited and often include comments on the architecture he viewed.

Postcards collected by Fred Willson dating from 1905-1933 primarily depicting images of buildings, churches, bridges and other major European architectural works. A large number of the cards were sent to Willson and his parents by a French Cleric, L'affi Didice. Willson likely met Didice through Jacobus Mandeville, a mutual friend, while visiting St Martin's abbey in Drome, France sometime in late 1904. The Didice cards date from 1904-1913 and 1923-1929. The cards depict images of France and sites that Willson visited during his 1904-1906 tour of Europe. Didice often mentions the weather, mundane tasks like chopping wood and other correspondence with the Willsons. Some cards were used to send holiday greetings to both F. Willson and his parents. There are several cards sent from Willson to his parents during his European tour. Willson often mentions sites he visited, his friend Jacobus and other Americans he met while in Europe. The cards date from 1904-1906 and depict images of city life, hotels and restaurants he visited, and major sites such as the L'Arc des Tuileries in Paris and the Coliseum in Rome. Willson also kept in his collection cards sent from friends visiting Europe, several blank postcards from France, a card sent from his son Lester and a card sent to Jacobus Mandeville from Didice. These cards largely depict Architectural works and date from 1905-1933. Some of the cards are in French and most contain greeting and brief information on what the traveler had seen during their journey. The card from Didice to Jacobus mentions that Didice had received correspondence from F. Willson and Willson is described as a friend of Jacobus. The original postcard collection was both loose and mounted. They are now arranged chronologically in three divisions. Division 1 contains cards sent from L. Didice to Fred and his parents, division 2 contains cards sent from Fred to his parents and division 3 contains cards sent to Fred from others, 1 postcard from Didice to Jacobus Mandeville and miscellaneous other postcards.

The collection of printed materials collected by Willson includes: a copy of the New Testament owned by Emma Willson; newspaper articles, both loose and in a scrapbook; a copy of The Montana Engineer; printed ephemera; and material relating to F. Willson's 1902 graduation from Columbia University. The newspaper clippings primarily date from 1920-1940 and relate to major architectural works or projects that Willson was involved with or interested in, such as the Belgrade City hall, the county jail in Butte and the Gallatin County High School. The papers represented include the , and the . Some full issue newspapers were retained if Willson did not indicate which column he intended to clip, while others in particularly bad condition were photocopied and discarded.

Business and personal correspondence, copies of "The Parade Passes," an address book and other assorted documents. The business correspondence is limited to 9 letters dated 1921-1926. They include requests for catalogs, booklets, portfolios and one document dealing with a proposed apartment building in Casper, WY. Many of the letters have hand written notes, calculations and diagrams written on the back of the pages. "The Parade Passes" was a paper Willson presented to the Bozeman Quest for Knowledge Club on February 16, 1954. The paper contains a general history Bozeman and of major events in Willson's life. He commented on a wide variety of topics including Mormons, shopping centers, television, saloons and the coronation of Queen Elizabeth. The L. Didice letters were sent to Willson between 1925-1926. The letters contain personal reflections on life and aging, talk of the political situation in France after WWI and discussion of L. Didice's family and his over twenty-year friendship with Willson. The Floyd Smith paper on the life of F. Willson is undated and provides a basic biography of Willson's life through the 1920's.

The photograph collection consists of a photo album containing approximately 420 photos and a single folder containing loose photos. Some of the loose photos were found with the L. Didice letters described in series 4. Two of these are labeled: a photo of L. Didice and a photo of Willson's mother, Emma. The photo album contains photos primarily taken during Willson's 1904-1906 trip through Europe. They are undated but often labeled with place names and occasionally the name of an individual. The collection includes photos of NYC as seen from the ship as Willson left the U.S. for Europe, Emma Willson at the Hotel Bellagio, the Dome of Duomo in Florence, Italy, farmers in Sicily, and the Arc de Triomphe in Reims, France. There are also several photos near the end of the album that appear to be taken of family and friends in Montana.

333 architectural drawings covering a forty-six year period of Willson's career as an architect. The majority of the drawings represent work done in Montana including the Y.M.C.A in Whitefish, the Gymnasium at Gallatin County High School, the Masonic Building in Manhattan, and the Holy Savior Church in Butte. All drawings have been stored separately in flat cabinets that are unavailable for browsing access. Some original Willson drawing sets were donated to Montana State University as portions of different architectural collection accessions and have not been included with the sets described in this series. To assist researchers in identifying specific drawing sets, regardless of their location, a special online catalog is available. Click here for access to the Architectural Drawing Catalog.