In some countries, like in Paris, they have a lot of dilemmas with these two problems. But, they are trying to respect them, and they aren’t building any skyscrapers or modern structures inside the city. There are other capital cities in Europe that are more modern like Madrid, as they haven't got so many monuments, and they can live wherever they want.
In spite of this, there are other capital cities that have very old structures, like London, and they only want to preserve the city centre, and in the rest of the city they are building big skyscrapers. And, why are they doing that, there is only one reason: money.
All in all, we have to be sensible, we had got a very big crisis, and now countries need money, so the richest men in the world are investing in that. Europe also needs to be modern, but I think that cities were more beautiful before than now, with the old structures.
Glossary: skyscraper, dilemmas, investing, preserve.