Hello!
Work is progressing quite well on the upcoming first iteration of the ideology system. In brief, the way it's going to function is that once a city has a city hall, a customs house and a national bank, as well as fulfills certain conditions (city size etc.), it will be able to convert to a city state, from an ordinary city. This will make the city enter into a period of revolution, after which you will be able to select an ideology.
Each ideology comes with a set of pros and cons, special perks, and will unlock a set of specific buildings and decorations. Each of the buildings will provide bonuses as long as the current ideology is active. If the city goes through another revolution to change its ideology, the building will convert to a historical site and output culture that boosts tourism.
Each building's effects etc. is still undergoing tweaks, and will get additional perks, but in general this is what each new building will do:
Authoritarian buildings (Communism, Authoritarianism and Fascism)
The surveillance center will boost output from police stations. It also functions as a police station of sorts itself.
The propaganda center cuts the cost of implementing crime related policies.
Liberal buildings (Libertarian Socialism, Liberalism, Laissez-Faire Capitalism)
The media center boosts the maximum tourism capacity in the city. It also outputs culture. Texturing still underway. :)
The university of liberal philosophy cuts the cost of universities across the city and acts as a university as well, outputting scientists.
Conservative/traditionalist buildings (Fascism, Conservatism, Laissez-Faire Capitalism)
The center of tradition boosts culture output across the city and functions as an educational building (similar to a museum).
The house of constitution cuts the cost of business-related policy. The building acts as a wealth building, boosting value in surrounding neighborhoods.
Progressive/left buildings (Communism, Progressivism, Libertarian Socialism)
The treasury boost residential tax uptake and lowers tax related unhappiness.
The house of unions buildings cuts the cost of labour policy.
Order buildings (Communism, Authoritarianism)
The house of beaurocracy building boosts the effect of policies slightly.
The grand arena cuts the cost of baseball and football fields as well as tennis courts. It also acts as a stadium.
Economy buildings (Liberalism, Laissez Faire liberalism)
The stock exchange increases tax uptake from commercial buildings.
The grand library cuts costs of libraries city wide. It is also a library building in and of itself (roughly thrice the output of a normal library).
Tradition buildings (Fascism, Conservatism)
The grand place of worship boosts happiness across the city. It also functions as a sanctuary, boosting culture. (untextured in image)
The great museum of history cuts the cost of museums across the city. It is also a museum building, roughly 3x a normal museum.
Solidarity buildings (Progressivism, Libertarian socialism)
The institute of public health boosts output from clinics and hospitals.
The revolutionary plaza cuts the cost of plaza "buildings" and decorations.
As mentioned, there will be additional perks for each building, added in as everything gets tweaked over time.