When cardinals gather to vote for a new pope, the attention of the world will once again focus on the Sistine Chapel, a setting resplendent with art and full of history.

From the outside, the only sign of the conclave proceedings will emerge from the smokestack on top of the chapel’s roof. Barely visible from St. Peter’s Square, it is kept in the viewfinder of telephoto lenses until a new pope is elected and white smoke pours out.

Inside, the cardinals will be surrounded by visual reminders of humanity’s destiny and the church’s history.

The cardinals file into the Sistine Chapel, passing beneath Michelangelo’s frescoed interpretation of the beginnings of salvation history: creation, the fall of Adam and Eve and the flood.

They will be flanked by paintings of God’s attempts to win back his people and save them: on one wall, the life of Moses; on the other, the life of Christ, including a painting of him handing over the keys of heaven and earth to St. Peter, the first pope.

Past the table where the cardinals will deposit their ballots and behind the main altar rises Michelangelo’s massive reminder of how each person will end his or her days: “The Last Judgment.”

In his 2003 book of poems, “Roman Triptych,” Pope John Paul II wrote about participating in the two 1978 conclaves in the Sistine Chapel.

Aware of God’s love and human frailty, the pope wrote, the cardinals must let themselves be led by God in their deliberations for a new pope.

“He (God) will point him out,” he said.

Even after the Sistine Chapel was built and its decoration completed by Michelangelo in 1541, not all papal elections were held in the chapel.

Pope Pius VII was elected in Venice, Italy, in 1800.

The four conclaves that followed (from 1823 to 1846) were all held in Rome’s Quirinal Palace, once the summer home of the popes and now the residence of the president of Italy.

While the art and fame of the Sistine Chapel make it almost unthinkable that a conclave would be held anywhere else, the chapel presents two small problems.

The first is space. At the 1978 conclaves that elected Popes John Paul I and John Paul II, some of the 111 participating cardinals complained that their seats were so close together they barely had room to breathe, let alone write a secret ballot.

While the chapel has about 5,600 square feet of floor space, the room is divided by a marble and iron screen, halving the space for setting up tables and chairs in a way that allows all the electors to see each other and the altar.

The smoke signal—the only form of communication between the electors and the outside world—also proved problematic in 1978.

A special stove and chimney were installed in the chapel in the middle of the 18th century.

The black smoke, which signals a ballot without a definitive outcome, was produced by burning the ballots with wet straw or, later, by adding chemicals. The white smoke that tells the world a new pope has been elected is produced by burning the ballots alone.

But weather, atmospheric conditions and pollution all make the signal difficult to decipher. Most people in the past have relied on confirmation by Vatican Radio before looking for a good spot in St. Peter’s Square to see the newly elected pope when he appears on the balcony of St. Peter’s Basilica.

To facilitate communication, the election of the next pope will be announced by the joyous ringing of the bells of St. Peter’s Basilica, in addition to the traditional white smoke from the chimney of the Sistine Chapel, a Vatican official said.

The bells ought to remove any doubt about the voting results, “so that journalists can be sure” that a new pope has been elected, Archbishop Piero Marini, master of papal liturgical ceremonies, said at a Vatican briefing April 5.