Given the task definition and input, reply with output. This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Passage: On October 1, 1989, a peaceful demonstration of 10,000 to 15,000 people was violently dispersed by the militia in front of Lviv's Druzhba Stadium, where a concert celebrating the Soviet "reunification" of Ukrainian lands was being held. On October 10, Ivano-Frankivsk was the site of a pre-election protest attended by 30,000 people. On October 15, several thousand people gathered in Chervonohrad, Chernivtsi, Rivne, and Zhytomyr; 500 in Dnipropetrovsk; and 30,000 in Lviv to protest the election law. On October 20, faithful and clergy of the Ukrainian Autocephalous Orthodox Church participated in a synod in Lviv, the first since its forced liquidation in the 1930s. Question: Prior to the October 20 synod, when was the last one held in Lviv?
1930s