Warner Brothers 

The Warner Brothers' first theatre, the Cascade, is often listed as predating the Nickelodeon in Pittsburgh. However Sam Warner once stated that he attended  a show at the Nickelodeon in 1905 with brother Harry, which inspired them to enter the movie business. 


The Warners in front of the Cascade

Acquiring a projector the brothers traveled the coal fields of Pennsylvania and Ohio presenting movie exhibitions. They finally settled in the town of New Castle, Pennsylvania where they set-up a 99 seat storefront theatre called the Cascade. 
The site was chosen because the Warners thought the exterior, with a gingerbread arch supported by pillars, had a theatrical appearance.
Ninety-nine chairs were borrowed from the local funeral parlor. Capacity was decided by local ordinance--anything over 100 seats required safety features.   
It was truly a family-run business with Sam operating the booth while sister Rose provided piano accompaniment for the various one-reelers. Brothers Harry and Albert handled the administrative end. Some accounts credit sister Sadie as selling the tickets.
As for baby brother Jack, he provided in-house entertainment with songs and dramatic sketches. According to family legend, this helped to clear the theatre between shows. 
The year is frequently given as 1903 or 05. The Harry M. Warner Film Institute and the Warner Sisters (formed by Cass Warner, granddaughter of Harry) gives the date as February 2,1907.

In addition to being the founder and president of Warner Sisters, Cass Warner is also the writer director of The Brothers Warner (2008):

 

The above photo of the Cascade is from the Harry M. Warner Film Institute

A replica of the original Warner's theatre is now part of the Cascade Center at the Riverplex, an indoor and outdoor shopping, dining, and entertainment complex.