When one goes to a place or a building for the purpose for which it is constructed, the definite article THE may be avoided.

• He is in jail.
  (i.e., he is convicted of an offence and undergoing punishment)
• Renz has gone to school. ( to study)
• Soja has gone to church. (to pray)
• He is in hospital (for treatment)

Now differentiate with THE:

• The magistrate is in the jail (may be he has gone to the jail to make an official visit)
• Neethu has gone to the school (perhaps to meet her kid’s class-teacher)
• The mason has gone to the church. (for doing some brick-work)
• He is in the hospital (i.e., to visit his injured friend)

However there is one exception to this:

• He went to the office. ✓
• He went to office. ✗