The particle は is used to identify the topic of the sentence, emphasizing the information about the noun that precedes it.長崎は、世界の平和を考える場所です。
Noun + が + passive verbN4
The particle が is used to emphasize the subject of the action in passive sentences, and is often used when the subject is the one being chosen or being acted upon.長崎と沖縄が選ばれました。
Noun + に + なりますN5
Express a change of state, to become, to get.首里城が新しくなります。