Source: Michigans Historic Sites Online
The Adrian Union Hall/Croswell Opera House, completed about 1866, is a two-story, rectangular structure constructed of red brick laid in common bond. (Two adjacent commercial buildings that now house theater functions are not included in the historic designation.) The roof is gabled with a low pitch. The cornice is adorned with a corbel table. The stage housing at the end of the auditorium was extended upward and outward in 1896, increasing the fly gallery and stage depth. The 1896 extension is clad in grey asbestos shingle. The side facades each had six round-head windows on the upper story and six segmental-arch-head windows on the lower story which have been filed in with brick.
The original facade had a round-arch entrance, executed in polychrome brick, which was concealed in 1882 when a small, brick vestibule was added. Extending from the 1882 vestibule to Maumee Street is a long, narrow lobby built in 1919 concealing the ornamental facade of the vestibule. The facade of the lobby was completed in 1921, and a marquee installed two years later. The lobby is one-story in height with a low-pitched gable parapet set between two brick piers. The surface is of brick with limestone detail. Below the parapet, which is supported by brick piers and a steel beam lintel, is a recessed entrance. The present interior, executed in a restrained Neo-Classical style, dates from the 1921 renovation.
The Croswell Opera House is significant for its architecture which, though dating from several different periods, forms a continuum reflecting significant changes in American entertainment forms and the corresponding changes in architectural tastes and function. The Croswell Opera House is also significant for its interrupted career as an entertainment center, among the oldest continuously operated in Michigan, which boasts and impressive list of artist who performed there. Furthermore, the structure is directly linked to Charles M. Croswell, two-time governor of Michigan (1877-1881) and prominent Adrian citizen. In 1863, Croswell, then a prominent lawyer in Adrian, purchased land at the center of town and formed an association to undertake the construction and management of a new theater, first known as the Adrian Union Hall.
The theater hosted a variety of entertainments and notable artists including Edwin Booth, Maude Adams, John Philip Sousa, Thomas Nast, and James Whitcomb Riley. As a large hall facility, it also hosted numerous social events, served as a roller skating rink, and housed the local Baptist congregation while their church was being reconstructed after a fire. The 1921 renovation was directed by architect John C. Brompton of Three Rivers. From 1921 until 1967, the opera house was known as the Croswell Theater and was used primarily as a motion picture house. Since 1967, the Croswell Opera House and Fine Arts Association has managed the opera house as a live theater with regular winter and summer theatrical series as well as a regular lecture series and schedule of community events.