Jönköping castle and fortifications, Medieval castle ruins in Jönköping, Sweden.

Jönköping castle and fortifications no longer stand above ground; the site is marked by later buildings. The County Administrative Board building and the Per Brahe Upper Secondary School now occupy the former castle area, while the foundations of the Great and Small Armoury buildings remain in Rådhusparken. A section of the eastern curtain wall was uncovered at Magnus Ladulås plats and preserved in the park.

A Franciscan monastery founded in 1283, probably on the initiative of Magnus Ladulås, stood here; Swedish and Danish representatives met in it in 1439 to depose Erik of Pomerania. After the Reformation the crown took over the buildings, and from 1544 Gustav Vasa had them converted into a castle, a direct response to the Dacke uprising of 1542–43. Burned in 1567, it was rebuilt with bastions Gustavus, Carolus, Adolphus and Christina, and a fire in 1737 ended it; the last ramparts were levelled in 1871.

The site's name recalls a fortress that no longer stands: nothing of the castle or ramparts survives above ground. The former stronghold area now holds the county administrative building, the old police house, Per Brahegymnasiet and the governor's residence. In Rådhusparken the foundations of the two great arsenal buildings, Stora and Lilla tyghusen, remain.

No remains of the castle or fortifications are visible above ground today. The site is marked by later buildings: the Länsstyrelsen building, the Per Brahegymnasiet, the old police house and the Residenset. In Rådhusparken, the foundations of the Stora and Lilla tyghusen remain, and part of the eastern curtain wall is preserved and visible at Magnus Ladulås plats.

No remains of the castle or fortifications are visible above ground today. Archaeologists have instead traced the fortification works: in 2002 parts of the Västerport gate were examined, and its walls are now marked in the paving by Hamnparken. A section of the eastern curtain wall, uncovered at today's Magnus Ladulås plats, was preserved and made visible after a local campaign.