What was involved in the building of a gate?

The author writes, They laid its beams and set its doors, its bolts, and its bars. Building a gate would involve (re)constructing the stone walls on either side of this access point to the city and then fastening timbers into the stone on which eventually to hang the doors. Bolts and bars would need to be added to secure the doors at night or in the event of an attack. It stands to reason that when the Babylonians captured and destroyed the city, all timber work at the gates were burned (2 Chronicles 36:19).