First Interstate Center is a signature commercial office building located in the Transwestern Plaza, a complex consisting of four office towers with a total of 35 floors, three 5 floor buildings and one 20 story tower, in the downtown core of Billings, Montana, United States. It is the tallest in the state of Montana and the tallest in the northern Rockies within the US. It was built in 1985 and rises to 272 feet. It is used primarily for office space.