Q. What is it supposed to be on the show? A. A temporary, mobile police command center, bringing together police, fire, ambulance and Homeland Security. Q. Where is it supposed to be on the show? A. In downtown Miami. Q. When did we see it on the show? A. In Episode 12, the Season 6 finale: "This is the Way the World Ends". Based on a drawing of a man atop a mountain, Debra has figured out that Travis is likely to strike one last time, sacrificing some innocent during the upcoming eclipse. Since there are no mountains in Miami, her guess is that Travis will opt for the top of one of the tallest skyscrapers in downtown Miami - at the moment of the eclipse.  So she stations cops atop each of them. In these scenes, standing in a sea of uniforms and emergency vehicles, Debra briefs her fellow cops on what they're looking for, and gives them a pep talk, sending them out to get Travis. It's also from here that she communicates, via radio, with the guards she has placed atop each of the skyscrapers. ( Unfortunately, Travis kills one policeman, and uses his walkie-talkie to convince Debra that things are OK atop the Transcorp Building. ) We also see the area when Debra phones Dexter about Travis's scheme, while Dexter is at his son's preschool pageant.

Q. Where can I find it in real life?

A. This parking lot is located at the northwest corner of Long Beach Blvd and 1st Street, in Long Beach, CA.

All they did was bring in a host of emergency vehicles, painted in Miami colors and logos.  They set up a tent, a few bulletin boards, a lot of uniformed extras, and they were ready to roll.

This parking lot is right across the street (kitty-corner) from the tower they used as the Transcorp Building.

And they shot the scene of Travis walking with the kidnapped Harrison on the sidewalk that runs along this parking lot's eastern edge.

The aerial photo below was shot during filming by Rick's brother, Jeff, from the Comerica building:

I shot the photos below, also during filming:
(The camera is looking north from 1st Street.)

[ Click on the photos to see larger versions ]

Here is an aerial photo of the location.  Here is a Google StreetView.
  And here is a map link.

A.  In previous seasons, I've usually had to hunt down the locations after viewing the episodes, using clues from the various scenes.  By the 6th season, though, I'd developed a small group of fans, spies & tipsters who kept an eye out for Dexter filming in their neighborhoods, and would let me know in advance when something was about to film there.

Between those reports, my own personal reconnaissance around town, and a few new resources I discovered, by the time the first episode aired, I already knew most (but not all) of the filming locations, and only needed to watch the episodes and match up the scenes with the correct locations.

This group of helpful fans includes Kerry, Rick, Ellen, Susan, Jason, Elaine, Joel, Julie, Geoff, Jeff, Jen, and others. My thanks to all of them.

Rick first alerted me that they would be filming here.  So I drove past and shot photos of the action.  Later, several fans reported back to me on the action.

And, as luck would have it, Rick's brother, Jeff,  works at the Comerica building, watched some of the filming, and got the photo you see above of the police command center.  (Small world, isn't it?)