Vacant Office Space status

[Carlos Ptriawan]

For officespace/commercial realtor out there: I saw a lot of office building that after the dot-com bubble in 2002, is still empty. The building looks good, etc as I know there're security and patrols.

But what's the purpose of maintaining such a building without a tenant for so long ? what actually happens to CRE that doesn't have a tenant for a such long period of time?