Oops, it doesn't look like 'assembly building on the day' is a national day..

Other days

ponytail

Ponytail Day
ask out your crush

Ask Out Your Crush Day
bounce

Bounce Day
stress awareness

Stress Awareness Day
chocolate milkshake

Chocolate Milkshake Day
eat what you want

Eat What You Want Day
cuddle up

Cuddle Up Day
china

China Day
law

Law Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day