I couldn't find a listing for the Riverside.
A year later, a Gazette story placed the Nickelodeon at 33 South Main and mentioned two additional downtown theaters, the Five Cent and the Unique.12
The 1909 Wright's Directory put the latter at 303 West Milwaukee which is the same address as the Orpheum, a theater I encountered looking through the 1910 Wright's Directory for Janesville.
(Note: In case you don't know [I didn't], according to answers.google.com: "The name 'Orpheum' for an entertainment hall comes from the Greek myth of Orpheus, whose music and poetry were so compelling that even the Gods were mesmerized. The word 'Orpheum' means 'house of Orpheus' or 'place of Orpheus.'"13)
I looked through several years of Wright Directories from the 1906 to 1910 but didn't find an address for the Five Cent.
Most of these small theaters were in the same west-of-the-river area as the last theater built downtown, the Jeffris, the one I attended most.
Myers Opera House
Van Pool also mentioned the Myers, located at 118 East Milwaukee Street, which opened in 1870 as the Myers Opera House and was remodeled in 1887, only to be destroyed by fire in 1889.14 It was rebuilt and reopened in 1891, as the Myers Grand Opera House15 and began showing movies during the first world war.16
According to EADS' Illustrated History of Janesville, Wisconsin, published in 1884: "In 1870, the "Myers Opera House was erected at a cost of $25,000." 17 An online inflation calculator estimates this at a little more than $454,000 in 2016 dollars, which seems low.18
An article published in the Gazette in 1922, titled "When Myers Opera House was Opened 52 Years Ago It Was One of the Very Best," mentioned that the first structure seated 750, "took seven months to build,” and was designed by "Architect [Edward Townsend] Mix of Milwaukee, who later drew plans for the Plankington Hotel in Wisconsin's largest city." 19
Mix was born on May 13, 1831, in New Haven, Connecticut. After establishing a practice in Milwaukee in 1856, he became the Wisconsin State Architect in 1864 and served until 1867. He died September 2, 1890, in Minneapolis. 20
An 1886 remodeling was accomplished at "...a cost of $35,000, making [the Myers] the finest in the state at that time," the Gazette reported in 1922. 21 Remodeling at $10,000 more than the cost of constructing the original building further makes suspect the $25,000 listed in the EADS' Illustrated History.
Myers fireThe fire that destroyed the first Myers occurred on February 20, 1889—an event reported in the Gazette under the headline, "A Bank Of Ice Ruins": "The ruins of the opera house today presented a melancholy sight. The rear wall and that on Bluff Street were down to the first story. The front wall, with the window frames burned away remained standing. The interior was a mass of iron girders and steam and gas piping." 22
John B. Myers, son of Peter Myers, the deceased builder of the Myers, said the fire started in "...the janitor's room from an overheated stove." He added: "I think our loss will be between $50,00 and $60,000. Father paid $22,000 for remodeling the opera house three years ago. We have no insurance." 23
The $22,000 figure is different from the $35,000 cost the paper reported in its 1922 look back.
1909 Wrights Directory
Janesville, Wisconsin page 269
1911 Wrights Directory
Janesville, Wisconsin page 221