14th century

after 1300	The previous town fortifications, consisting of palisade-crowned ramparts and ditches, are replaced by a continuous stone wall 3 to 4 meters high.
1301	The foundation of the Cistercian monastery is completed. The parish of Jena and the church of St. Michael - which thus fulfills a dual function as a town and monastery church - are transferred to the monastery by the Lobdeburg town lords.
1304	The castles of the Kirchberg burgraves on the Hausberg are stormed and destroyed by a landgrave's peace order (with the participation of a Jena contingent). The Kirchbergers subsequently lose their function as a territorial power. A building inscription gives the first indication of the Johannistor as a stone gate building. Its present appearance is that of a new building from the 15th century.
1305	Burgau Castle - until then the seat of a collateral line of the Lobdeburgs - is identified as the property of the Wettin dynasty.
1307	May 23: St. John's Cemetery is first mentioned as a burial ground outside the town wall. Another cemetery near the church of St. Michael within the city walls is used until the 16th century. June 21: A priest is named for Wenigenjena for the first time.
1315	April 11: The Lobdeburg-Elsterberg quarter of Jena falls to the Wettins. August 16: The documentary mention of the Saalmühle mill documents the existence of the "Lache" as an artificial arm of the Saale in front of the Saaltor. Originally part of the town fortifications, it is now mainly used to operate mills.
1316	November 19: The mill located at Johannistor within the town, later known as the "Jüdenmühle" because of its location in Jüdengasse, is mentioned for the first time.
1317	A town council, presided over by two council masters (mayors), is mentioned in a document.
1319	May 26/27: The town council and St. Michael's Monastery reach an agreement on the establishment of the "Hospital of the Holy Spirit and All Saints" in front of St. John's Gate. June 1: The Löbdertor, the Marktmühle and the Teufelslöcher near Wöllnitz ("foramen diaboli") are mentioned for the first time.
1320	July 22: The first documentary evidence of the use of stones in the construction of the Saale bridge in the area of today's Camsdorf bridge is recorded. The Brückenhof Foundation is established for the construction and maintenance of the bridge. Over time, it is endowed with numerous plots of land and interest and also receives income from the council village of Jenalöbnitz and as the lord of the court in the villages of Ossmaritz and Vollradisroda. The bridge yard is managed by the bridge master under the supervision of the town council.
1321	September 7: The mention of Güntherus Gewantsnyder in a document refers to the cloth-making trade in the town.
1328	January 6: Leutra is mentioned for the first time as a suburban settlement in front of the Johannistor. The place (with St. John's Church and St. John's Cemetery) is probably not identical with the "Liutdraha" mentioned in the Hersfeld tithe register at the end of the 9th century. March 28: The first reference to the system of three "rotating" councils is documented. According to this system, one of the three councillors acts as acting ("sitting") councillor every three years, while the members of the other two councils perform advisory functions.
1331	February 6: With the sale of the second half of Jena by the Lords of Lobdeburg-Leuchtenburg, the entire city falls to the Thuringian landgraves from the House of Wettin.
1332	April 24: Landgravine Elisabeth, to whose widow's estate the town belongs, grants Jena the town charter of Gotha. This finally establishes Saxon law for Jena. The new town charter contains the first reference to the town's brewing rights.
1333	April 11: A mention of the library of the Dominican monastery indicates the existence of a monastery school in Jena.
1337	The Rasenmühle is mentioned for the first time. This also documents the existence of the artificial Rasenmühle island surrounded by the Saale river and millrace.
1338	July 25: Heinrich Cerdo (= tanner) is the first documented evidence of the tanning trade in Jena.
1344	November 18: Zweifelbach is mentioned for the first time as a southern suburb in front of the Löbdertor.
1346	November 21: Nollendorf is mentioned for the first time as a northern Jena suburb.
1350	March 19: Landgravine Elisabeth hands over the rule of Jena to her grandson Frederick the Strict.
after 1350	A narrative cycle of 78 paintings with biblical themes is created on the outer wall of St. Nicolai's Church in Lichtenhain. The artists, whose names are unknown, were inspired by models from south-western Germany.
1352	January 29: In return for a loan granted by the Landgrave, Jena is temporarily given the office of mayor, the mint and customs.
1353	January 6: A landgrave's decree grants permission to expand and fortify the town towards the Saale. The "Vorstadt auf dem Sande" in front of the Saaltor (also: "Hodelsdorf") is created. The hospital is moved here from Johannistor and dedicated to St. Nicholas. The hospital's assets are linked to the Brückenhof Foundation and co-administered by the bridge master.
1354	July 22: St. Michael's Monastery and the City Council share the offerings for the St. Nicholas Chapel to be built in St. Nicholas Hospital. The corresponding contract mentions the Saaltor and three fairs held in Jena for the first time.
1355	April 12: The city council consists of ten councillors and two council masters (mayors). This composition of the council remains the norm until the beginning of the 19th century.
1358	The Kirchberg care of Windberg (with Wenigenjena/Camsdorf, Ziegenhain, Jenaprießnitz, Wogau) as well as Lobdeburg Castle and the town of Lobeda fall to the Wettins.
1364	1 March: The craftsmen organized in guilds are involved for the first time in a contract between St. Michael's Monastery and the town council, which stipulates the involvement of the town council in filling the position of schoolmaster.
1365	February 8: The landgraves pledge customs and the town court to the town council, with the exception of the court over the neck and hand. The town council is given a say in the appointment of judges, which had previously been the sole responsibility of the sovereign. Subsequently, the judge is always appointed from the ranks of the town council.
1367	January 1: The annual rent to be paid to the sovereign as a municipal tax since 1332 is increased from 100 marks to 120 marks.
1368	June 12: A town hall - a predecessor of the Gothic town hall built a short time later - is mentioned for the first time.
1377	March 10: The butchers' stalls (Fleischbänke) on the first floor of the town hall are mentioned for the first time.
1378	June 11: St. Michael's Monastery grants permission to erect an altar with a perpetual mass in the town hall.
1379	April 24: Jews are documented as residents of Jena.
around 1380	Construction of the new Gothic Jena town church - as it appears today - begins. The Dominicans compile a register of the dead, in which people connected with the monastery are recorded with their date of death (and sometimes with additional information). It is kept until the abolition of the monastery in 1525.
1380	January 30: The function of town clerk is mentioned for the first time.
1383	A "districtus Burgow", recorded for the first time in sources, forms the starting point for the creation of an office in Burgau and thus for the establishment of an official administration in the area around Jena.
Between 1385 and 1390	The so-called Jena Pietà, a vesper painting in the beautiful style from Prague (now in the town museum), was created.
1391	November 30: A bakehouse near the town church of St. Michael is documented.
1393	The nuns of St. Michael's Convent have their own brewery. The rafting of the Saale near Jena is mentioned in a document.
1395	May 17: The master craftsmen are given the right to control the accounts of the municipal officials.
1399	March-May: Supra-regional trade in Jena wine is documented. Wine growing and trade as well as related trades and services form the main source of income for the Jena population.