Go early! When you get to HR to check in, you will be given a sheet of questions. It is a great/important idea to spend time penciling in your answers before the interview. Know that they collect the page afterwards though... you don't keep it (public disclosure) so if you do want to keep it, take a photo with your phone before going into the interview.

One thorough interview, with a panel of three senior level city employees representing Finance, IT, etc. The initial reception in the municipal tower was very standardized. They request the interviewee to show up 1 1/2 hrs prior to the panel interview in order to complete a more technical exercise and familiarize with the interview questions (yes, they provided the actual interview questions upon check-in). The exercise was to draft a memo outlining a business impact analysis plan for the city's first data center migration.