Minecraft wiki entry for Building_a_metropolis, associated text: Cinema/Theater Build a large building with a ticket counter and a hallway leading to the screen rooms. Have a food bar selling "popcorn" (pumpkin seeds) and "cola" (milk buckets or potions). You can also have actors or pistons and redstone moving things about. There could be a dark cave under the seats for monster sound effects, or a note block circuit or jukebox for music. Try to have different types of screen like 'low class', 'medium class' 'high class' and (possibly) IMAX (huge proportions!).
City/Town Hall This is probably the first building players usually make when building a metropolis. Have a huge building for the mayor, the mayor's assistants, and the people in charge of certain things (such as law enforcement, health and welfare, ...) A good place to put this is the very heart of your city. You can have an auditorium and the city's archives located in this building. You could even build a huge political complex around it with a secret service headquarters, embassies for mobs or other cities or servers, and of course, parking for everyone.