Any building gets old after some period of time. But this does not mean that we have to knock down all old buildings. Some of them are worth standing for ages, some not, because their spiritual, architectural and financial value is not the same.
To start with, I think it is good to have old buildings because of their architectural worth. They are important for scientists who study architectural styles. Of course not all buildings are useful. The apartment blocks, foor example. They were built 50-60 years ago, but many people agree that they should be destroyed. These buildings are physically and morally old, unsafe to live and distort the face of the city.
On the other hand, nobody would like to knock down such apartment blocks like those in The Old Towns. They are worthy not only architecturally, but also spiritually. They seem to have their own spirit. They are alive, not like those built in the Soviet times.
What is moore, many old buildings are useful financially. Lots of tourists come to visit The Old Towns of different cities, lonely castles standing somewhere on a hill or even the monasteries in the mountains. But we cannot reject the fact that it
To sum everything up, I think people have to choose which building to knock down and which to save according to its architectural and financial worth.