If you visit London, go to the British Museum, the oldest public museum in the world.
The zero conditional form is used when we talk about things that are generally or always true.
Note that we are not talking about a specific event but something which is generally true.
If/When/Unless plus a present form + present simple or imperative
For example:
If we don't recycle:
If you don't recycle paper, the trees that make our oxygen won't last so much longer.
If you recycle cans, the energy that would have been used to make more cans will be saved.
When you recycle, space in landfills are saved.
Also, things such as plastic bottles can last up to 1 million years.
The best thing to do is re-use as much of these things as we can.
If we didnt recycle land fills will fill up.
