Riemannian geometry is the branch of differential geometry that studies Riemannian manifolds, defined as smooth manifolds with a Riemannian metric. This gives, in particular, local notions of angle, length of curves, surface area and volume. From those, some other global quantities can be derived by integrating local contributions.
The Dordtse Kil is a short river in South Holland in the Netherlands. The river is tidal and forms the connection between the Oude Maas river and the Hollands Diep. The river is for most part artificial in origin, since it has been a relatively small tidal creek until the 19th century.
The White Tower of Thessaloniki is a monument and museum on the waterfront of the city of Thessaloniki, capital of the region of Macedonia in northern Greece. The present tower replaced an old Byzantine fortification, known to have been mentioned around the 12th century, that the Ottoman Empire reconstructed to fortify the city's fortress some time after Sultan Murad II captured Thessaloniki in 1430. During the period of Ottoman rule, the tower became a notorious prison and the scene of numerous mass executions, most famously of the Janissaries who revolted during the reign of Mahmud II.
Tallinn TV Tower is a free-standing structure with an observation deck, built to provide better telecommunication services for the 1980 Moscow Summer Olympics regatta event. It is located near the suburb Pirita, six km north-east of the Tallinn city center. With its 313 m (1030.2 ft), the TV tower is the tallest nonbuilding structure in Tallinn. The tower was officially opened on 11 July 1980. The viewing platform at a height of 170 metres was open to the public until 26 November 2007, when it was closed for renovation. The tower began receiving visitors again on 5 April 2012. The building is administered by the public company Levira and is a member of the World Federation of Great Towers.
The Fernmeldeturm Nürnberg, the tallest structure in Bavaria, is a telecommunication tower in Nuremberg, southern Germany. Also called the Nürnberger Ei because of its egg-shaped tower basket in a height of 185 metres, it is 292 metres high and was built between 1977 and 1980 according to blueprints by architect Erwin Heinle.
The Maunsell Forts are armed towers built in the Thames and Mersey estuaries during the Second World War to help defend the United Kingdom. They were operated as army and navy forts, and named after their designer, Guy Maunsell. The forts were decommissioned during the late 1950s and later used for other activities including pirate radio broadcasting. One of the forts is managed by the unrecognised Principality of Sealand; boats visit the remaining forts occasionally, and a consortium named Project Redsands is planning to conserve the fort situated at Red Sands. The aesthetic attraction of the Maunsell forts has been considered to be associated with the aesthetics of decay, transience and nostalgia.
HM Fort Roughs is one of several World War II installations that were designed by Guy Maunsell and known collectively as His Majesty's Forts or as Maunsell Sea Forts; the purpose of which was to guard the port of Harwich, Essex, and more broadly, the Thames estuary. This 4,500 ton artificial naval installation is similar in some respects to "fixed" offshore oil platforms. It is situated on Rough Sands, a sandbar located approximately 11 kilometres (6 nmi) from the coast of Suffolk and 13 kilometres (7 nmi) from the coast of Essex. Today it is the location and de facto capital of the unrecognised, self-proclaimed state of Sealand.
Pfalzgrafenstein Castle is a toll castle on the Falkenau island, otherwise known as Pfalz Island in the River Rhine near Kaub, Germany. Known as "the Pfalz", this former stronghold is famous for its picturesque and unique setting.
Van Hauen Pass is a mountain pass on northwestern Ellesmere Island, Nunavut, Canada.
The Münden Nature Park lies within the district of Göttingen, in south Lower Saxony in Germany.
The Großer Steinberg is a 493 m above sea level (NN) high hill in the south of the Solling range. It lies within the district of Northeim, in the southwestern part of the German state of Lower Saxony.
The Dresden Panometer is an attraction in Dresden, Germany. It is a venue displaying one of two panoramic paintings of Austrian-born artist Yadegar Asisi inside a former gasometer, accompanied by an exhibition. One of the two panoramas, Baroque Dresden depicts Dresden as it might have appeared in 1756, the other, Dresden 1945 shows the city after it was destroyed during World War II. The Panometer was created in 2006 by Asisi, who coined the name as a portmanteau of "panorama" and "gasometer". In 2003 he had opened a Panometer in Leipzig.
The Mechelen-Zuid water tower is a 143-metre-high (469 ft), combined water and telecommunications tower constructed in 1978. Since 1979, it has supplied the water to the city of Mechelen, Belgium, while also hosting television and telecommunications aerials. The concrete spire passes through a wide disc holding water fifty metres above the ground. Higher up, a smaller disc supports telecommunications equipment. Topped by a decorative stainless steel tube, it is claimed to be the highest water tower in the world.
The Dransfeld Municipal Forest is situated on a ridge in Germany's Central Uplands that ascends to 480 m high. It is located in the district of Göttingen, in South Lower Saxony. Although its name suggests a forest within a town, Dranfeld Municipal Forest is actually a small, heavily forested high ridge that lies about halfway between the city of Göttingen to the northeast and the town of Hann. Münden to the southwest; it is east of the Bramwald and immediately south of the city of Dransfeld. The B3 federal highway runs through the western foothills of the Dransfeld Municipal Forest, located in the northern part of the Münden Nature Park.
The Hoher Hagen is a volcanic hill that is still 480 m high today, in the Dransfeld Municipal Forest, in the German district of Göttingen in South Lower Saxony.
The Mackenröder Spitze, at about 427.5 m above sea level (NN), is the highest hill in the Göttingen Forest and lies on the boundary of the town and district of Göttingen, in South Lower Saxony in Germany.
Stein Mountain, elev. 2761 m, is a mountain in the Lillooet Ranges of southwestern British Columbia, Canada, located northwest of the confluence of the Stein and Fraser Rivers, which is just upstream from the town of Lytton. Its name derives from that of the Stein River.
The Emperor William Tower or Kaiser Wilhelm Tower is an observation tower near Holzminden in the German state of Lower Saxony, built in honour of the German emperor, William I. It was erected in 1908 and is 17 metres high.
Semnan Space Center is the primary Iranian spaceport, located 50 km southeast of the city of Semnan in the north of the country.
Mustankallio water tower lies in the Kiveriö district of Lahti, Finland, and stands 50 metres (160 ft) tall. Completed by a local company in 1963, it includes two water reservoirs, a penthouse meeting facility complete with sauna, and a viewing platform. The design, which features pre-stressed concrete elements and asbestos cement cladding, was a departure from the steel water tower structures commonly built in the region. When commissioned, its original name was the Metelinmäki Water Tower. It has been described as crocus-like in appearance and complimented on its elegance.
