Every so often somebody asks about the corroding civil defense sirens up on poles scattered all over Los Angeles. Well, Dennis Hanley knows all about them. They were air raid sirens first installed during World War II, then revived and expanded during the Cold War of the 1950s and 60s. Most people who lived here then remember the sirens being tested on the last Friday of every month at 10 a.m. The system was shut down for good in the 1980s, but something like 200 of the big metal sirens remain as dormant reminders of the years when officials prepared for Soviet attacks. Hanley chronicles the sirens at his website. Saul Gonzalez talked to him recently for KCRW.