Watchtower in the context of "Limes Arabicus"

The Great Wall of China (traditional Chinese: 萬里長城; simplified Chinese: 万里长城; pinyin: Wànlǐ Chángchéng, literally "ten thousand li long wall") is a series of fortifications in China. They were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic groups from the Eurasian Steppe. The first walls date to the 7th century BC; these were joined together in the Qin dynasty. Successive dynasties expanded the wall system; the best-known sections were built by the Ming dynasty (1368–1644).

To aid in defense, the Great Wall utilized watchtowers, troop barracks, garrison stations, signaling capabilities through the means of smoke or fire, and its status as a transportation corridor. Other purposes of the Great Wall have included border controls (allowing control of immigration and emigration, and the imposition of duties on goods transported along the Silk Road), and the regulation of trade.

San Fruttuoso Abbey (Italian: Abbazia di San Fruttuoso) is a Romanesque religious building located in a secluded bay in the Italian Riviera near Genoa, between Camogli and Portofino, The abbey used to be under the patronage of the Genoese aristocratic Doria family, who protected it with a watchtower built by the architect Giovanni Ponzello in 1562.

It is the seat of the Catholic parish of San Fruttuoso di Capodimonte, belonging to the Vicariate of Recco-Uscio-Camogli of the Archdiocese of Genoa.

An observation tower is a tower used to view events from a long distance and to create a full 360 degree range of vision to conduct long distance observations. Observation towers are usually at least 20 metres (66 ft) tall and are made from stone, iron, and wood. Many modern towers are also used as TV towers, restaurants, or churches. The towers first appeared in the ancient world, as long ago as the Babylonian Empire.

Observation towers that are used as guard posts or observation posts over an extended period to overlook an area are commonly called watchtowers instead.

A castellum in Latin is usually:

• a small Roman fortlet or tower, a diminutive of castrum ('military camp'), often used as a watchtower or signal station like on Hadrian's Wall. It is distinct from a burgus, which is a later Latin term that was used particularly in the Germanic provinces.
• a distribution, header, and settling tank for municipal water in a Roman aqueduct (known as a castellum aquae/castellum divisorium).

It is the source of the English word "castle".

Rammed earth, also called pisé, is a technique for constructing foundations, floors, and walls using compacted natural raw materials such as earth, chalk, lime, or gravel. It is an ancient method that has been revived recently as a sustainable building method.

Pisé also refers to a material for sculptures, usually small and made in molds. It has been especially used in Central Asia and Tibetan art, and sometimes in China.

The Galata Tower (Turkish: Galata Kulesi), officially the Galata Tower Museum (Turkish: Galata Kulesi Müzesi), is a medieval Genoese tower in the Galata part of the Beyoğlu district of Istanbul, Turkey. Built as a watchtower at the highest point of the mostly demolished Walls of Galata, the tower is now an exhibition space and museum, and a symbol of Beyoğlu and Istanbul.

The Danubian Limes (German: Donaulimes), or Danube Limes, refers to the Roman military frontier or limes which lies along the River Danube in the present-day German state of Bavaria, in Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria and Romania.

The Danube was not always or everywhere used by the Romans as the military frontier which was moved north or south in some locations according to military conquests, but it was maintained in many places as a fairly permanent defensive structure for long periods. The border was reinforced with numerous watchtowers, legion camps (castra) and forts (castella). Due to the boggy and dendritic nature of the Danube's river banks no border ramparts were built, unlike the Neckar-Odenwald Limes in Germany. The camps were built in the mid-1st century. Later, under Trajan, the camps, which had originally only been surrounded by earthen embankments, were enclosed by stone walls.