The old telephone office building housed the bank until 1920, when it moved into its beautiful new building, which was designed by famed architect Louis Sullivan. Sullivan has been called the father of the skyscraper, but probably his true genius is best seen in the small bank buildings he designed. The bank in Columbus is his last work. It is said that he called it his "jewel box".

J. Russell Wheeler, the grandson of the founder of the Bank, commissioned Sullivan to design the bank. Wheeler initially bowed to the trend to Greek classical style in seeking a design for his bank. However, Mrs. Wheeler was not so influenced by the Greek style. She persuaded her husband to scrap his original plans and call on Sullivan . She had seen photographs of banks he had built in Ohio and Minnesota and was deeply impressed. The Wheelers never regretted their decision.  Louis Sullivan became their friend, staying at their home many times when he came to town to check on the progress of the building.

The Bank which resulted from the Wheeler-Sullivan relationship is a little oblong building. It is built of a soft shade of red brick, highlighted with touches of blue. Wheeler reported that Sullivan was very particular that the bricks be selected at random so as to give a casually shaded effect. The narrow horizontal lines echo the Prairie style that Frank Lloyd Wright — a student of Sullivan's — was later to make famous. The simple cube of the bank's exterior is elaborately ornamented in terracotta which is glazed in a pale green and is moteled with specs of brown. Its most impressive feature is the entrance way. Here a series of archways recede to form a frame for the stained-glass windows that lights the interior shades of yellow and green and ruby red. Below the archway a marble lintel bears the name of the bank and its architect on either side, elaborately framed in the delicate geometric design and curling leaf tendrils that are Sullivan's trademark, are the dates 1861 and 1919. The bank was founded in 1861 and the new building put up in 1919. Two lions stand guard above the lintel each proudly holding a shield. Three square ornamented tellers support the lintel and at the center of the front and rear of the building are two identical eagles. All along the side of the building a series of ornamented archways surrounds stained glass windows. These are buttressed at either end by square block pillars. The interior of the building has about it a quiet, cool air of efficiency. There is a small wrought iron set of movable steps so that children can reach the teller windows. The drinking fountain carries at its top a garland of leaves and flowers that could only have been designed by Sullivan. Upon completion of the building in 1919, Louis Sullivan presented the lamp with a stained-glass shade that still sets where he placed it in the lobby.

The Guggenheim Foundation commissioned John Szarkowski in the mid nineteen fifties to take innumerable photographs, both of the exterior and interior of the bank, some of which are now on exhibition in the bank lobby.

In the late fifties, a teacher at the University of Wisconsin, Edward Kamarch, wrote a play about the building of the bank and the Wheelers who were instrumental in getting Sullivan to design it. The play, "The Jewel Box" was presented in the Memorial Union Theatre in Madison in February of 1959 with many people associated with the bank in attendance.

In 1958 an addition was built to the bank, fortunately in complete keeping with the original structure. The architects for the addition were Law, Law, Potter and Nystrom of Madison. Sullivan's blue prints were in the vaults of the American Terra Cotta Company which had provided the original artwork for the building. Thus, it was possible to make plaster of Paris molds of clay replicas of the decorative moldings and friezes designed by Sullivan. One of the greatest difficulties of making the new elements was to reproduce the original color as far as possible.  Much of the original work had faded from the 30 years of exposure to air and light.  An "average" color had to be used in the new work.

On October 18, 1972 the bank was entered on the NATIONAL REGISTER OF HISTORIC PLACES and is therefore accorded the benefits and protection of the National Historic Preservation Act of 1966.  

In 1980 the newest addition to the bank was completed.  The addition stands as a separate storefront where the old Tezlaff Drug Store used to stand.  It is a streamlined, modern structure with smoked glass windows and is an obvious contrast to Sullivan's jewel box.  A small museum was built on the mezzanine floor to display architecturally significant materials from the Louis Sullivan era.  An additional drive-up teller unit and walk-up windows were also added.

The bank now attracts architecture students at frequent intervals who come to study and admire the last work of a man who forever changed the nation's architecture.  The staff of the bank are used to people taking photos and asking questions.