JenTower

The Johannistor is the only remaining preserved city gate of the city of Jena, Thuringia, Germany. As part of the medieval city wall, it is connected to the Pulverturm (a tower, also preserved) via a reconstructed walkway. The outer gate remained in existence until the beginning of the nineteenth century, when it was demolished as a result of increasing traffic. Until the houses lining the south side of Johannisstrasse were demolished in 1968, the Johannistor remained the only western entrance to the old town of Jena.

Jena (German pronunciation: [ˈjeːna] ) is a city in Germany and the second largest city in Thuringia. Together with the nearby cities of Erfurt and Weimar, it forms the central metropolitan area of Thuringia with approximately 500,000 inhabitants, while the city itself has a population of about 110,000. Jena is a centre of education and research; the university (now Friedrich Schiller University) was founded in 1558 and had 18,000 students in 2017 and the Ernst-Abbe-Fachhochschule Jena counts another 5,000 students. Furthermore, there are many institutes of the leading German research societies. Jena was first mentioned in 1182 and stayed a small town until the 19th century, when industry developed. For most of the 20th century, Jena was a world centre of the optical industry around companies such as Carl Zeiss, Schott and Jenoptik (since 1990). As one of only a few medium-sized cities in Germany, it has some high-rise buildings in the city centre, such as the JenTower. These also have their origin in the former Carl Zeiss factory. Between 1790 and 1850, Jena was a focal point of the German Vormärz as well as of the student liberal and unification movement and German Romanticism. Notable persons of this period in Jena were Friedrich Schiller, Alexander von Humboldt, Johann Gottlieb Fichte, Georg Wilhelm Friedrich Hegel, Novalis, and August Wilhelm Schlegel. Jena's economy is largely built upon its high-technology infrastructure and research. The precision optical instruments industry is its leading branch to date, although software engineering, other digital businesses, and biotechnology are of growing importance. Furthermore, Jena is also a service hub for its regional environs. Jena lies in a hilly landscape in the east of Thuringia, within the wide valley of the Saale river. Due to its rocky landscape, varied substrate and mixed forests, Jena is known in Germany for the wide variety of wild orchids which can be found within walking distance of the town. Local nature reserves are maintained by volunteers and NABU.

The University of Jena, officially the Friedrich Schiller University Jena (German: Friedrich-Schiller-Universität Jena, abbreviated FSU, shortened form Uni Jena), is a public research university located in Jena, Thuringia, Germany. The university was established in 1558 and is counted among the ten oldest universities in Germany. It is affiliated with six Nobel Prize winners, most recently in 2000 when Jena graduate Herbert Kroemer won the Nobel Prize for physics. It was renamed after the poet Friedrich Schiller who was teaching as professor of philosophy when Jena attracted some of the most influential minds at the turn of the 19th century. With Karl Leonhard Reinhold, Johann Gottlieb Fichte, G. W. F. Hegel, F. W. J. Schelling and Friedrich Schlegel on its teaching staff, the university was at the centre of the emergence of German idealism and early Romanticism. As of 2014, the university has around 19,000 students enrolled and 375 professors. Its current president, Walter Rosenthal, has held the role since 2014.

The Botanischer Garten Jena (4.5 hectares) is the second oldest botanical garden in Germany, maintained by the University of Jena and located at Fürstengraben 26, Jena, Thuringia, Germany. It is open daily; an admission fee is charged. The garden was first established in 1586 as a hortus medicus, six years after the establishment of the Botanical Garden in Leipzig in 1580. In 1630 it was rearranged and expanded significantly by Professor Werner Rolfinck who had previously studied at the Orto botanico di Padova (founded 1545). In 1640 a second section (1.3 hectares in area, north of the city walls) was donated, and a catalog from 1659 documents over 1300 plants in the two gardens. In 1662 the original garden was expanded, with the first heated greenhouse added in 1674, at which time the garden first began to maintain a collection of tropical plants. In 1770 the garden introduced Linnean taxonomy, and in 1776 Goethe began his association with the garden and helped organize the Jena Institute of botany; over subsequent decades he often studied botany and wrote poems in the garden. Although the garden area was only 1.3 hectares at this time, purchases recorded in 1794 include Buxus sempervirens, Juniperus sabina, Periploca graeca, Sambucus racemosa, and Thuja occidentalis. Several years later, additional purchases included amaryllis, cacti, succulent Euphorbia, Pelargonium, and Zantedeschia. The garden's first published catalog issued in 1795. Unfortunately, the garden was severely damaged in 1806 in the Napoleonic Battle of Jena-Auerstedt, and its recovery was long and slow. By 1819 the garden contained only some 50 potted plants in one greenhouse and approximately 200 outdoor plants. However, in 1820 an additional greenhouse was constructed, and the existing greenhouses reorganized to become an orangery, palm house, and cold house. The garden was thoroughly reworked between 1877 and 1879, after which it contained 2020 species from 85 families as well as a medicinal garden and 13 groups of potted plants from geographically distinct regions. As of 1966 this number had grown substantially to about 2000 families, to which were added a further 300 families (more than 3000 species) in a new alpine plant collection. Today the garden contains about 12,000 plants. Its outdoor areas include an arboretum containing about 900 species of deciduous and coniferous trees and shrubs; an alpine garden representing approximately 2,500 species; a systematic garden organized by contemporary taxonomy; a collection of medicinal and useful plants; a small hill and pond; and a collection of rhododendrons, roses, and dahlias. Its five greenhouses are as follows: cactus and succulent house; cold house for the transitional zone between tropics and subtropics; palm and tropical house; "evolution" house with ancient plant forms including cycads and tree ferns; and a tropical aquatic house which contains Victoria cruziana, mangroves, epiphytes, etc.

Astrophysikalisches Institut und Universitäts-Sternwarte Jena (AIU Jena, Astrophysical Institute and University Observatory Jena, or simply Jena Observatory) is an astronomical observatory owned and operated by Friedrich Schiller University of Jena. It has two main locations in Jena, Germany and the neighbouring village of Großschwabhausen.

The Zeiss-Planetarium in Jena, Germany, is the oldest continuously operating planetarium in the world. Engineered by German engineer Walther Bauersfeld, the building was opened on 18 July 1926.The Zeiss-Planetarium is a projection planetarium; the planets and fixed stars are projected onto the inner surface of a white cupola. It is owned and operated by the Ernst-Abbe-Stiftung.

Jena Phyletisches Museum (or Jena Phyletic Museum) is a museum in the German town of Jena. It was established by the scientist Ernst Haeckel, as an institute dedicated to explaining evolution to the public. Exhibits include skeletons, stuffed animals, fossils and zoological artworks from Haeckel's Kunstformen der Natur, and cover topics including the principles of evolution, biodiversity and the links between different taxonomic groups. A temporary exhibit for 2019 will feature an aquarium of living jellyfish.

The Volkshaus in Jena was one of the first free educational institutions in Germany to be set up on the North American model.

Jena Paradies station is the main railway station of the city of Jena in the German state of Thuringia. It is on the Saal Railway and is served by two long-distance services each day and regional trains to and from Naumburg, Saalfeld and Pößneck. It is named after and adjacent to Paradies ("paradise") Park, which is on the eastern shore of the Saale river.

The Deutsches Optisches Museum Jena is a science and technology museum displaying optical instruments from eight centuries. It gives a technical and cultural-historical survey of the development of optical instruments. The development of the city Jena to the centre of the optical industries since the mid-19th-century is integrated in the exhibition, connected with the lifeworks of Ernst Abbe, Carl Zeiss and Otto Schott. In cooperation with the art club Jena non-optical themes are offered in special exhibitions. Before the opening of the Zeiss Museum of Optics in Oberkochen in 2014, the Deutsches Optisches Museum Jena was the only museum of its kind in Germany.

Leutra is a small river in Thuringia, Germany. It flows into the Saale in the centre of Jena. Another small river also named Leutra flows into the Saale in the village Maua (part of Jena), 6 km to the south.

Oriental Coin Cabinet Jena (German: Orientalisches Münzkabinett Jena) is a collection of oriental coins at Jena University, in Jena, Germany, founded in 1840.