In Evony you get 22 building spots inside each of your town. It is very essential to have as much barracks as possible to generate troops much faster. So, you have to know which building can be replaced with barracks and when.
I am explaining which buildings you can delete and when you can delete them.
Market - You should keep a market in one of your city and delete them from the other cities. You buy buy resource in that city and send them other cities.
Inn - Inn is the place where you can recruit heroes. You can recruit heroes from the inn and reinforce them to othere cities. So , keeping an Inn in every city is not very necessery.
Warehouse - Warehouse is not very necessary if you have more than one city . When under attack you can send gold and food very quickly from another city using scouts, for prying and loyalty increasing. So, you don't waste space for warehouse.
Workshop - Workshop is required in each city to develop walls. You can demolish the workshop when your walls reach level 10.( This is only for age 1, in age 2 you can no longer demolish workshops. if you do that u will loose the hero gear effect in that city)
Stable - You can build one stable in one city for completing the Horse back riding and upgrading relief station. Research Horse Back Riding only in that city where you have built the stable. Once you have level 10 Horse Back Riding you can delete the stable.
Forge - Forge is required for researching Military Science. When your Military Science reaches at 10 you can delete forge. Again , instead of building stable and forge in all your cities , you can build forge in one city and research military science there and build stable in another city and research Horse Back riding there.
Feasting hall- If your city is only for producing troops and you never attack anyone or NPC's then there is no need for keeping Feasting Halls in that city.
Buildings that you must keep in all your cities.
Cottages - You should keep at least 6 cottages in all your cities.
Academy - You must keep academy of same level in each city. If you keep higher level academy in one city and low level academy in another then the city with lower level academy will not get the benefits of high level researches.
Rally Spot - Without a rally spot you can not send troops to another city or attack.
Beacon tower - Without a beacon tower , you won't have information about the attacking troops. if someone attacks your city which has no becon tower you not be able to know what amount of troops are attacking you.
Embassy - If you don't have an embassy then your alliance members can not sends troops to your city for reinforcements.
Relief Station - without a relief station sending troops to another city will take a very long time.
