Art Gallery Day has one instruction. Go to a gallery.
Choose a room near you. It can be a place you already know, or a door you have walked past. Stay long enough to look at one work properly. If someone from the gallery is there, thank them.
That visit is the day. It is how the public shows it understands what galleries do: they are the reason a great deal of art leaves the studio and meets a stranger.
Sunday 15 August 2027 is the next Art Gallery Day. The day returns every 15 August, in every city that has a gallery.