In church architecture, the lantern tower is a tall construction above the junction of the four arms of a cruciform (cross-shaped) church, with openings through which light from outside can shine down to the crossing (so it also called a crossing lantern).
Many lantern towers are octagonal and give an extra dimension to the decorated interior of the dome.
An affiliated term is the Italian , which is the lantern atop a dome. Like a lantern tower, a is often polygonal and interspersed with windows both to lighten the load and allow for light to shine. The word is from the Medieval Latin (, a variant of ).