Apart from a Roman Fort, there were very few fortifications in Alderney until the mid 19th century. These were then modified and updated in the mid 20th Century by Germans during the occupation period. Alderney island is now one of the most fortified places in the world.
The Victorian era fortifications were built after 1845 against the naval threat from France. Completed in 1855, Fort Clonque, the most westerly in Alderney, connected by a causeway, mounting ten guns with a crew of 59 and bomb proof buildings. Originally the barracks were on the shore, making it impossible to get to the fort to man the guns at high tide.
Fort Tourgis was also completed in 1855. It was the second largest fort on the Island, mounting 33 guns in five batteries requiring 346 men. Sufficient accommodation was available in the fort. Built on a headland covering the bays of Clonque and Plattes Saline with many loopholed walls. Along the second beach, two batteries were built, Platte Saline and Doyle with three and four guns. Used by the Alderney militia until it was disbanded in 1882 and the militia artillery until 1929.
There are around ten more smaller forts as well built by British armies.
Arriving in an almost deserted island in 1940, all but 18 of the population having evacuated to England, the 450 Germans manned the existing fortifications until in 1941 when a decision was made by Adolf Hitler to fortify the Channel Islands. The majority of the work was given to the Organisation Todt. Workers were brought to the Island and installed in camps. The four camps by January 1942 held 6,000 workers.
Camp Sylt held Jews who were treated as slaves and camp Norderney held forced labour mainly Russian and Polish POW's but including men from many other nationalities were run by the OT until the SS took them over in March 1943. Those that survived the harsh treatment were shipped back to France to work on the Atlantic Wall when that became a higher priority. There are 397 known graves in Alderney and about 200 died when two German minesweepers were sunk by two Allied Destroyers on 7/8 July 1944.
References:Monte d"Accoddi is a Neolithic archaeological site in northern Sardinia, located in the territory of Sassari. The site consists of a massive raised stone platform thought to have been an altar. It was constructed by the Ozieri culture or earlier, with the oldest parts dated to around 4,000–3,650 BC.
The site was discovered in 1954 in a field owned by the Segni family. No chambers or entrances to the mound have been found, leading to the presumption it was an altar, a temple or a step pyramid. It may have also served an observational function, as its square plan is coordinated with the cardinal points of the compass.
The initial Ozieri structure was abandoned or destroyed around 3000 BC, with traces of fire found in the archeological evidence. Around 2800 BC the remains of the original structure were completely covered with a layered mixture of earth and stone, and large blocks of limestone were then applied to establish a second platform, truncated by a step pyramid (36 m × 29 m, about 10 m in height), accessible by means of a second ramp, 42 m long, built over the older one. This second temple resembles contemporary Mesopotamian ziggurats, and is attributed to the Abealzu-Filigosa culture.
Archeological excavations from the chalcolithic Abealzu-Filigosa layers indicate the Monte d"Accoddi was used for animal sacrifice, with the remains of sheep, cattle, and swine recovered in near equal proportions. It is among the earliest known sacrificial sites in Western Europe.
The site appears to have been abandoned again around 1800 BC, at the onset of the Nuragic age.
The monument was partially reconstructed during the 1980s. It is open to the public and accessible by the old route of SS131 highway, near the hamlet of Ottava. It is 14,9 km from Sassari and 45 km from Alghero. There is no public transportation to the site. The opening times vary throughout the year.