Colosseum Construction?

A little clarity. What exactly are you asking? There is always a certain amount of maintenance on going most of the time.

I read somewhere. They said the exterior come down and the next, it will be interior, will start to construction

There has been a cleaning/restoration project ongoing at the Colosseum for several years. When I was there in 2009, it was looking pretty dingy. (I guess two millenia can do that.) In 2013, most of the structure was covered with scaffolding. When I returned last May, only the southeast portion still had some scaffolding, but the rest of the building looked much cleaner.

Looking back at the photos of my first Europe trip (1968), it's remarkable how much brighter and cleaner most European cities and monuments are now than they were then.

The work is going on in small sections, so most of the Colosseum is available for visitors.

I visited the Colosseum last June and there was some minor construction along the outside but it didn't get in the way of our tour.

I was there in late September and only a portion of the outer wall was being cleaned. I was very pleased with how it is now looking. You should have no problems with the restoration of the Colosseum. You can check webcams on just about any site in Italy. That might give you some idea on what is going on.