Ok, I consider 100 years ago from the top of my head pretty reasonable, especially as someone who couldn’t care less about a foreign monarch or precision in dating architectural styles. But, regardless, it’s not referring to an era but to an architectural style. While it was most popular 120 years ago, there have been Victorians built since then. I know not every Victorian in SF is 120+ years old because the city was burned to the ground in 1906.