Sometimes, even in representational art, all is not quite as it appears. Scroll on to pull back the curtain and reveal some of art history's secret codes and hidden messages...

Painted in 1888, Café Terrace at Night is one of Van Gogh’s most famous works. The image shows a street in the French city of Arles. The artificial light from the nearby café illuminates much of the scene, while the background is dotted with windows and the sky lit up by stars. 

Some experts have speculated that this is actually Van Gogh’s version of The Last Supper. The central, Jesus-like figure is surrounded by 12 people, one of whom, like Judas, is slipping off into the shadows. There also appear to be a number of crucifixes dotted around the scene, emphasising the work's religious overtones.

This brings us neatly to The Last Supper itself, painted by Leonardo da Vinci in the late 15th century (shown here in a 1520 copy by Giampietrino). One of the most famous artworks in the world, the painting has long been the subject of speculation and creative interpretation. 

One popular theory is that the layout of the bread and crockery on the table is supposed to represent musical notes. When put together, these create a short 40-second hymn. Having music hidden within the piece definitely helps to bring the work to life and gives us a tantalising glimpse into the creative mind of Da Vinci. 

Painted by Hans Holbein the Younger in 1533, The Ambassadors is one of the most famous works from the Tudor period. Almost every object in the picture is there to symbolize something, making this a favorite for code breakers everywhere. 

The most intriguing secret contained in this painting can be found right at the front of the image – an anamorphic skull that can only be seen clearly when viewed from the correct angle. A stark memento mori, it also shows off Holbein's talent with perspective. 

Netherlandish Proverbs was painted by Pieter Bruegel the Elder in 1559. The busy scene is filled with people and animals, many of which tell the stories of old Dutch proverbs. In fact, the painting is so action packed, you can spot a saying or phrase almost everywhere you look.

Many of these sayings are still in common use. For example, this man here is ‘banging his head against a brick wall’. 

While this figure is ‘swimming against the tide’.

And this man is ‘armed to the teeth’.

Altogether, there are around 126 proverbs and idioms contained within the image, though it’s possible the scene contains more sayings that have since fallen out of use. This makes it one of the most code-packed paintings around. 

Hanukkah is the eight-day-long Jewish festival of lights that commemorates the story of the Maccabees reclaiming their Holy Temple after a three year war with the Greeks. To celebrate their victory they lit an oil lamp and, even though they only had enough oil for one day, the lamp miraculously burned for eight days and nights. 

Now when the celebration comes round every year it’s tradition to light the candles on a Hanukkah menorah, or Hanukkiah, on each night of the festival. 

Hanukkah is one of the more well known Jewish holidays, but it isn’t mentioned in the Torah and is termed a ‘minor’ holiday because, unlike Rosh Hashana or Passover, it doesn’t require major restrictions on people’s behavior and eating habits.

However, there are culinary traditions that go hand in hand with the celebration, such as oily food eaten as a symbol of the miracle oil that burned for eight days. 

The most common way to spell the name of the holiday is Chanukah or Hanukkah but there are actually 16 different ways it can been transliterated into English because of the guttural “hecht” sound of the first Hebrew letter of the word.

A Hannukkiah holds nine candles, one for each night of the festival and one that’s raised above the rest. The ninth higher candle, known as the shamash, is lit first then used to light the others. Each candle traditionally burns for at least half an hour.

There are at least 44 candles in each box of Hanukkah candles. On the first night, only one candle (plus the shamash) is lit, on the second night two are lit, and so on until the Hanukkiah is fully lit on the final night. 

Before the advent of instant communication, the best way to reach people was through the mail. Scroll to see correspondence from notable figures around the world!

Frida Kahlo, one of Mexico's most beloved artists, was also a prolific writer of letters. She hand-wrote letters to friends, lovers, and relatives throughout her life, like the one addressed to Leon Trotsky painted here. This 1937 piece resides at NMWA in Washington DC.

Frida wrote this letter to her husband, the painter Diego Rivera, in 1940.

...and sealed it with a kiss.

Frédéric Chopin was a shooting star in the world of music, composing hundreds of pieces for piano in his brief 39 years. Maximilian Fajans created this lithograph in the decade after Chopin's death.

Chopin penned this letter to his pupil Marie de Rozières and said, "country-house life in high society is really very interesting. They have nothing like it on the continent."

Florence Nightingale, a British statistician and activist, laid the foundation for modern nursing. After a spiritual experience, she dedicated her life to helping people--caring for soldiers during the Crimean war, founding the first secular nursing school, and much more.

In this letter to her cousin Marianne Nicholson, she describes the vision which inspired her lifelong quest of service. You can read a transcript of the letter courtesy of Leeds Museums & Galleries.

Vincent van Gogh's storied life is well documented in his numerous letters to friends and relations, though the lion's share of the surviving correspondence is addressed to his brother Theo.