What walks on four legs in the morn- wait, what do you mean you've heard that one before? Have you been talking to Oedipus? Alright, smartypants, then how's this for a riddle: Who am I?

I am a rock group with four members. All dead, one was assassinated. What am I?

From the Fun Historical Riddles department: Where was the Declaration of Independence signed?

A natural hole in the wall, or a void buried and warded A site of memory for time before history recorded

Let's get down to brass tacks. Historically used to signal battle or hunt, I'm the best instrument there is to be blunt. If you want to announce something loudly, there's no instrument better than me I'll say proudly.