The precision optical instruments industry is its leading branch to date, although software engineering, other digital businesses, and biotechnology are of growing importance.

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.

Nevertheless, there were also some more important Saale crossings such as the nearby cities of Naumburg to the north and Saalfeld to the south, so that the relevance of Jena was more local during the Middle Ages.

The first local rulers of the region were the Lords of Lobdeburg with their eponymous castle near Lobeda, roughly 6 km (4 mi) south of the city centre on the eastern hillside of the Saale valley.

Around 1230, Jena received town rights and a regular city grid was established between today's Fürstengraben, Löbdergraben, Teichgraben and Leutragraben.

As the political circumstances in Thuringia changed in the middle of the 14th century, the weakened Lords of Lobdeburg sold Jena to the aspiring Wettins in 1331.

Ernestine Elector John Frederick the Magnanimous founded it, because he had lost his old university in Wittenberg to the Albertines after the Schmalkaldic War.

[7] In 1794, the poets Goethe and Schiller met at the university and established a long lasting friendship, based on their love of Shakespeare.

Zeiss, Abbe and Schott worked also as social reformers who wanted to improve the living conditions of their workers and the local wealth in general.

In 1898 it was agreed on with several personalities from the Jenaer industrial sector that the city was in need of an electricity generator[9] and in the first years of the 1900s an electrified tramway was founded in Jena.

Industry came into a heavy crisis during the 1990s, but finally it managed the transition to the market economy and today, it is one of the leading economic centres of eastern Germany.

The mountains belong to the geological formation of Ilm Saale Plate (Muschelkalk) and are relatively flat on their peaks but steep to the valleys in between.

Due to its jagged surface, the municipal territory isn't very suitable for agriculture all the more since the most flat areas along the valley were built on during the 20th century.

The city's topography creates a microclimate caused through the basin position with sometimes inversion in winter (quite cold nights under −20 °C (−4 °F)) and heat and inadequate air circulation in summer.

Due to its distance to coastal areas and position in the Saale valley, wind speeds tend to be very low; predominant direction is SW.

The Jena weather station has recorded the following extreme values:[21] Jena abuts the district of Saale-Holzland with the municipalities of Lehesten, Neuengönna, and Golmsdorf in the north, Jenalöbnitz, Großlöbichau, and Schlöben in the east and Laasdorf, Zöllnitz, Sulza, Rothenstein, Milda, and Bucha in the south and the district of Weimarer Land with the municipalities of Döbritschen, Großschwabhausen, and Saaleplatte in the west.

[23] The most important regions of origin of Jena migrants are rural areas of Thuringia, Saxony-Anhalt and Saxony as well as foreign countries such as Poland, Russia, Ukraine, Hungary, Serbia, Romania, and Bulgaria.

Like many other eastern German cities, Jena has a small foreign-born population: circa 4.0% are non-Germans by citizenship and overall 6.2% are migrants (according to 2011 EU census).

The historic city centre is located inside the former wall (which is the area between Fürstengraben in the north, Löbdergraben in the east, Teichgraben in the south and Leutragraben in the west).

There are only a few historic buildings in this area (e.g. at Oberlauengasse), due to the destruction during World War II and modernization projects in the following decades.

The Eichplatz, a big sub-used square covering a large amount of the centre, has not been built on since the 1960s and the discussion about its future is still in process.

In these areas, some historic building structures from the 18th and early 19th century remained in western Bachstraße and Wagnergasse, in northern Zwätzengasse and in southern Neugasse.

With companies such as Intershop Communications, Salesforce.com (after the acquisition of Demandware) and ePages as well as several web agencies, Jena is a hub for E-commerce in Germany.

The city is among Germany's 50 fastest growing regions, with many internationally renowned research institutes and companies, a comparatively low unemployment and a young population structure.

Together with the photonics lab Lichtwerkstatt Archived 4 February 2018 at the Wayback Machine and the Krautspace there are makerspaces and hackerspaces enabling start-ups to create their product ideas and realizing their first prototype and business models as well as networking.

Both of these connect points of tourist interest: the former along the Saale valley from Fichtel Mountains in Bavaria to the Elbe river near Magdeburg, while the latter follows the medieval Via Regia closely and runs from Eisenach via Erfurt, Weimar and Jena to Altenburg via Gera.

Furthermore, there is an extensive network of buses, run (such as the trams) by the "Jenah" organization, a pun on Jena and the German Nahverkehr lit.

Another college is the Ernst-Abbe-Hochschule Jena, a University of Applied Sciences founded in 1991 which offers a combination of scientific training and its practical applications.

Another state-owned Gymnasium (the Carl-Zeiss-Gymnasium Jena) offers a focus in sciences also as an elite boarding school additionally to the common curriculum.

[27][28][29] The first freely elected mayor after German reunification was Peter Röhlinger of the Free Democratic Party (FDP), who served from 1990 to 2006.