The topic of the closed door in art is abundant. Many artists were fascinated from the mistery and the symbolism of a closed door. Ghiberti made one of the most impressive examples in the Renaissance, then Donatello chose the same motive for his "Annunciation". Maybe one of the most popular doors comes from Rodin: "The Gates of Hell" highlight Dante's Inferno as a romantic source of inspiration. 
In my personal version, the primary source is Ghiberti's "Porta del Paradiso" in Florence. Instead of the biblical scenes I have painted images that describe the burning issues of our time (climate change, the power of the empires, violence and revolutions, wars...), and instead of the saints and the prophets on the sides, I have painted artists and intellectuals who have influenced or represented the course of the modern Western history from my personal point of view (all in all, 44 heads and statues). They also give us the key to understand and foresee the development of the new millenium ahead... and open that door without fear.
Here below the complete list for each single door leaf: 

 

Left (counterclockwise):

 

Laura Bassi

Frida Kahlo

Nan Goldin

Edie Sedgwick

Marie Curie

Vandana Shiva

Clara Immerwahr

Leni Rifenstahl

Anguissola Sofonisba

Alda Merini

Artemisia Gentileschi

Ulrike Hermann

Elizabeth Jennings Graham

Naomi Klein

Mary Wollstonecraft

George Sand

Sara Teasdale

Ada Lovelace

Virginia Wolf

Elena Lucrezia Corner Piscopia

Mary Shelley

 

Right (counterclockwise):

 

George Seurat

Filippo Brunelleschi

Aldous Huxley

Galileo Galilei

Bertrand Russell

Marcel Duchamp

Roland Barthes

David Graeber

Baruch De Spinoza

Charles Darwin

Marshall McLuhan

Mohandas Karamchand Gandhi

Daniele Ganser

Martin Luther King

Karl Polanyi

Leonardo da Vinci

Edward Snowden

Sigmund Freud

Noam Chomsky

Giordano Bruno

Gerhard Richter

 

There are two more heads, actually... one is mine and it is in place of Ghiberti's own head on the original door...