Seaman Hall contained four stories and a basement, and had an oak-paneled fellowship hall, corporate offices, Sunday school rooms, a gymnasium, and a large kitchen and dining room. The acoustics were excellent, and the stage was well-equipped for first-class productions. Films could be shown on a huge theater-sized screen. However not all of Seaman's grand plans came to fruition. A bowling alley and rooftop garden were never finished.
Almost immediately the high costs of maintaining such a large ornate structure burdened the church. The Great Depression made things even worse, causing the church to lease parts of Seaman's hall to Gary College. By 1949, Indiana University Northwest occupied 3-floors of the annex.
Although the 1950s saw a peak in membership of over 3000, by the 1960s the congregation rapidly declined and the church was forced to cancel many community programs in order to save money. By 1973 only 320 members remained, with only 1/3rd attending service regularly. Mounting repair costs forced the church to finally close on October 5th, 1975.
After the Methodist Church abandoned the building, it was sold to Indiana University who continued to use Seaman Hall as a satellite campus. A large fire ravaged the area in October 1997, destroying most of the roof and leaving the building exposed to the elements. The city fenced the property in 1999 to prevent vandals and drug deals, to no avail.
Gary voted to demolish the church in 2005, however David Wright, the new city planner proposed saving the Gothic main sanctuary and allowing it to become a garden like ruin park. The plan included demolishing Seaman Hall, the office area and back area while salvaging the fixtures and decorative masonry to fund the demolition. However the plan was shelved when the city found that all items of value had already been scrapped.
Various parts of the roof collapsed after the fire, but the City deemed the church as being structurally sound. However a large portion of the main sanctuary roof collapsed in the Fall of 2014.
All information above taken from a really nice article, with great old photos here: http://sometimes-interesting.com/2013/06/16/city-united-methodist-church-of-gary-indiana/