They are amazing because they 1) look real 2) are completely flat but look 3 Dimensional 3) drawn only with chalk.
The author of these great drawing is a super creative person also known as Pavement Picasso whose name is Julian Beever.
Not to reinvent the wheel I will cite Wikipedia: “Julian Beever is an English chalk artist who has been creating trompe-l’œil chalk drawings on pavement surfaces since the mid-1990s. His works are created using a projection called anamorphosis, and create the illusion of three dimensions when viewed from the correct angle.
Beever works as a freelance performance artist and creates murals for companies.” Keep in mind that every sidewalk drawing is entirely flat!
Phew, that was an easy introduction! Enjoy the pictures, my friends.