They are Victorian bathing machines.
Bathers got changed inside, then descended a flight of steps to have a swim in the sea, without being seen by prying eyes.
The first bathing machine was used at Scarborough in the 1730s and they soon became popular all around the country.
Folkestone byelaws stated that a bathing machine used by a member of the opposite sex must be at least 20 yards away!
Here is a view of the whole beach
Have you ever seen so many people! Zoom in to see what they’re doing.