Chicago's all about preservation this week. Yesterday, Preservation Chicago released its annual list of endangered landmarks. Today, the once-gaping hole in Montrose Avenue has it's own MySpace page and will play host to a "Pro Hole Rally" at 4:45 p.m.

UPDATE 05/07: Tour 826Michigan "The Monster Union."

At 4:36 A.M. Friday morning, tremors swept across the Chicago area, lasting for about 15 seconds and shaking high rises. According to a dispatcher on the city information line, hundreds of people began calling in from across the city immediately to ask if it had been an earthquake.

In Old Town, emergency sirens began sounding just twelve minutes later as car horns honked from the streets. More on this developing story as it comes in.

UPDATE 4:59 A.M.: A reader, Ed, has posted a link to the seismograph.