This 140,000 SF, 13-story National Historic Landmark, designed by Louis Sullivan and built in 1895 and was modernized several times between the 1950s to 1970s.  

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Flynn Battaglia Architects has been involved with the restoration efforts since 1979.  In the 1980s the lost projected storefront was rebuilt from castings of original sections.  The rich terra cotta exterior was carefully cleaned with a mild detergent solution after the fabrication and replacement of more than 200 pieces of various shapes and sizes.  Original art glass ceiling panels, ornamental metals and the marble tessarae frieze was repaired and restored.  

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In 2000, new work at the Guaranty Building was needed to retain the restored features from the 1983 work as the building adapted from multi-tenant office space into single tenant offices for a large law firm.  Additionally, restoration efforts were needed for newly discovered deterioration in several areas.