Destroying the old buildings in a city can benefit citizens in many ways. When the government organizations or people destroy these buildings, citizens can build new fashionable buildings in such areas. If people continue such an approach, gradually the city becomes new and beautiful. Even so, there are few people how think that an old monument in a city must be destroyed because preserving such a building has many points in its favor. These monuments are attractive buildings and can attract tourists and be a resource of making money for citizens. In addition, they are parts of a city's history and must be preserved and rebuild because of their historical backgrounds.
Firstly, foreigners want to see monuments when they visit a new country or a new city. Only new buildings, markets, parks, or movie theaters are not enough to attract a tourist. They usually want to see something unique in the cities they visit. Almost all of the European or American's big cities have great markets and fashionable buildings, so when people from Europe and the United States visit Iran, they do not interested in visiting new buildings, that's why they usually visit Shiraz and Isfahan and don't visit Tehran. Shirazian and Isfahanian have preserved such buildings and now people from these cities enjoy from income they make from supply of goods and services to tourists.
Secondly, the old buildings are live documents of the history of a city and shouldn't be removed to build the new ones. Sometimes people destroy these buildings because they want to build some new attractive apartments or stores and sometimes they remove such buildings because of their beliefs. Recently in Afghanistan lots of statues and monuments from the ancient times were destroyed by Taliban because Taliban considered them as illegal. In Shiraz, on the other hand, citizens preserved Persepolis for a very long time because they think this monument is one of the most important historical buildings from the ancient times and must be preserved. Because of such a belief Shirazian always have stopped everybody that wanted destroy this monument. For a long time people didn't know the real history of Persepolis, however, recently some archeologists issued some interesting and important facts that they found in Persepolis about the history of Iran. In sum, I think we must stop anyone how want to remove an important old monument everywhere on the planet Earth.
In conclusion, although both preserving and destroying monuments can benefit citizens in different ways, in my view, preserving such buildings is preferable. We should take care of ancient buildings because they can be attractive for tourists, they can be resources for local people to make money, and they are the most important parts of a city's history.