How was pre-title opening in Spectre shot?

The opening scene in 2015's Spectre has a long continuous sequence which, as an amateur filmmaker, is difficult to figure out how it might have been done.

• The movie begins as an apparent crane shot over a Mexico City Day-of-the-dead parade.
• The camera slowly comes down to shoulder level while tracking a male/female couple in costume and masks walking against the parade toward the camera, then past it, and the camera follows them.
• They walk into a hotel and then an elevator with the camera following into the elevator.
• The elevator goes up a few floors, opens, and the camera backs out of the elevator. The couple follows the camera then transitions to walking ahead a few steps to a room, open it, and walk through. The camera follows them in (oddly closing the door for them as neither of them do).
• The couple takes off masks, there is some conversation between them as the woman goes into the bathroom and comes back to find, now clearly Bond, in street clothes with an equipment case.
• Bond climbs out the window and the camera follows through the window, then leads as he walks along old building ledges, etc.
• The camera climbs now evidently flying as there are openings several stories high below it. Bond walks several blocks on rooftops past the camera until he gets to his vantage point across from a building full of bad guys.
• The sequence finally has a jump cut to look into the bad guy building and then back to Bond.

I suppose with a $200+ million budget, they would think nothing of post-producing a montage of shots into a smooth, continuous flow. But I can't help wonder if they really did it in one shot, transitioning from quadcopter to steadicam and back for the shot?