A lantern, a word from the Latin lanterna,[1]​ in architecture, is a tube-shaped element arranged as a top on a dome, which through holes allows lighting "Lighting (architecture)") and ventilation "Ventilation (architecture)") of the interior space of the building. Its role is similar to that of the oculus, although it is less protected from the elements.

When the lantern does not rest on a dome but is directly a lighting tower part of the roof, it is called a tiburium or lantern tower. The lantern has also been used as a purely ornamental element, stripped of any practical use, and appears in different historicist architectures to be used as a finishing touch on roofs, towers and pinnacles.

With a circular or polygonal plan, it opens to the interior directly on the dome, without another structure to support it. Their function is to give light to the dome, through vertical walls on which windows open;[1]​ For this reason, and because of their similarity in shape, they are called "lanterns". A second function was that, by tending the hot air to rise, they acted as a chimney draft, removing the heat and smoke from the candles in the vault.

On the upper part of the lantern, a cross, a symbol of Christianity, is usually installed in religious buildings.

The lanterns are usually small in relation to the domes that support them. However, in important buildings, basilicas and cathedrals, they are true tempiettos and some of them are even accessible, through the structure of the dome, being true viewpoints, such as Santa Maria del Fiore in Florence. In other cases, its relative size in relation to the dome, as in the Roman Basilica of Saint Peter or Sant'Ivo alla Sapienza, acquires great compositional importance, even going so far as to mask the beginnings of the domes themselves to enhance their role.

From the Renaissance onwards, when the technique for constructing domes was improved, artists began to think of original shapes and solutions for lanterns, giving them maximum importance as distinctive elements that stand out in the sky. One of its introducers was Francesco Borromini, with his lanterns famous for their spiral development.