Here are two cities: The one on the left is an old city.

And the one on the right is a new city.

Do you notice any difference between them?

The biggest difference between them is that they are shaped differently.

The old city is shaped like a circle, and the new city is shaped like a rectangle.

Let's find out why these two types of cities have different shapes.

Many modern cities were built using a grid plan.

An example of a city built using a grid plan is Chicago in the United States.

The map of Chicago shows that all of its streets intersect to form a perfect grid.

All the streets runs perfectly parallel and perpendicular to one another.

On the other hand, many old cities have grown organically, or naturally with rounded curves.

A perfect example of an organic city is Moscow, Russia.

At the center of the city is the Kremlin, Russia's former royal palace.

Many years ago, city citizens began building shops and houses outward from the Kremlin in all directions.

Later, roads were built to connect the houses.

Since the roads were built later, they do not form a grid.

Instead, it is shaped like a circle.