Oops, it doesn't look like 'monument on a day' is a national day..

Other days

kale

Kale Day
donate your hair

Donate Your Hair Day
prosecco

Prosecco Day
camera

Camera Day
cat girl

Cat Girl Day
kiss a ginger

Kiss A Ginger Day
bubble bath

Bubble Bath Day
pumpkin

Pumpkin Day
gum

Gum Day
law

Law Day