The is one of two types of two-storied gate presently used in Japan (the other one being the nijūmon

Nijūmon

The is one of two types of two-story gate presently used in Japan , and can be found at most Japanese Buddhist temples. This gate is distinguishable from its relative by the roof above the first floor which skirts the entire upper story, absent in a rōmon...

, see photo in the gallery below). Even though it was originally developed by Buddhist architecture

Japanese Buddhist architecture

Japanese Buddhist architecture is the architecture of Buddhist temples in Japan, consisting of locally developed variants of architectural styles born in China...

, it is now used at both Buddhist temples

Buddhist temples in Japan

Along with Shinto shrines, Buddhist temples are the most numerous, famous, and important religious buildings in Japan.The term "Shinto shrine" is used in opposition to "Buddhist temple" to mirror in English the distinction made in Japanese between Shinto and Buddhist religious structures. In...

 and Shinto shrines. Its otherwise normal upper story is inaccessible and therefore offers no usable space. It is in this respect similar to the tahōtō

Tahōtō

A is a form of Japanese pagoda found primarily at Esoteric Shingon and Tendai school Buddhist temples. It is unique among pagodas because it has an even number of stories...

 (a two-storied pagoda) and the multi-storied pagoda, neither of which offers, in spite of appearances, usable space beyond the first story. In the past, the name also used to be sometimes applied to double-roof gates.

This extremely common single-roof gate was developed from the double-roofed nijūmon, replacing the flanking roof above the first floor with a very shallow balcony with a balustrade that skirts the entire upper story. Therefore, while the nijūmon has a series of brackets (tokyō

Tokyō

The Dougong in Chinese is a system of and supporting the eaves of a Japanese building, usually part of a Buddhist temple or Shinto shrine. The use of tokyō is made necessary by the extent to which the eaves protrude, a functionally essential element of Japanese Buddhist architecture. The system...

) supporting the roof's eaves

Eaves

The eaves of a roof are its lower edges. They usually project beyond the walls of the building to carry rain water away.-Etymology:"Eaves" is derived from Old English and is both the singular and plural form of the word.- Function :...

 both at the first and at the second story, in the rōmon at the first floor these brackets just support the balcony, and have a different structure. The tokyō are usually three-stepped (mitesaki

Tokyō

The Dougong in Chinese is a system of and supporting the eaves of a Japanese building, usually part of a Buddhist temple or Shinto shrine. The use of tokyō is made necessary by the extent to which the eaves protrude, a functionally essential element of Japanese Buddhist architecture. The system...

). The tokyō are usually three-stepped (mitesaki

Tokyō

The Dougong in Chinese is a system of and supporting the eaves of a Japanese building, usually part of a Buddhist temple or Shinto shrine. The use of tokyō is made necessary by the extent to which the eaves protrude, a functionally essential element of Japanese Buddhist architecture. The system...

), but at the first floor they don't have tail rafters.

Rōmon structure can vary greatly in its details. The upper area behind the balustrade for example can have muntin

Muntin

Muntin or Muntin bar is a strip of wood or metal separating and holding panes of glass in a window. Muntins are also called "glazing bars", "muntin bars", or "sash bars". Muntins can be found in doors, windows and furniture, typically in western styles of architecture...

ed windows or a single window in the center bay

Ken (architecture)

A is a measurement in Japanese architecture. It has two principal uses:* As a proportion for intervals between the pillars of traditional-style buildings. The word is translated in this case in English as "bay". Traditional buildings usually measure an odd number of bays, for example 3×3 or 5×5...

. Side bays can be covered with white plaster. Rōmon usually, but not always, have a hip-and-gable (irimoya

Irimoya

A xieshan style or roof in Japanese architecture is a hip roof integrated on two opposing sides with a gable. It can be also described in English as a hip-and-gable, gablet, or Dutch gable roof...

) roof. Dimensions go from Tōdai-ji

Todai-ji

, is a Buddhist temple complex located in the city of Nara, Japan. Its Great Buddha Hall , the largest wooden building in the world, houses the world's largest bronze statue of the Buddha Vairocana, known in Japanese simply as Daibutsu . The temple also serves as the Japanese headquarters of the ...

's 5 bays to the more common 3-bays, down to even one bay.