Also referred to variously and confusingly as the First and Second Defensive Rings, this is a ring of defences originally built between 1626 and 1634 to thwart the threat posed by Swedish King Gustav Adolphus.
Construction was led by mathematician Johann Strauss, Count Abraham von Dohna and surveyor Konrad Burck and when completed enclosed the city within a ring of defences 3.5km in diameter. The fortifications consisted of 32 Rondells and Ravelins, with two gates to the south and seven to the north of the Pregel river, most of which maintained their names through the rebuilding work of the 19th century.

With Prussia feeling an increased threat from Russia in 1841, a report was commissioned to clarify what needed to be done to fortify East Prussia. Generals von Grolmann, von Krausemeck and Aster reported their findings in early 1842 and a new series of fortifications, designed by Chief Engineer Leopold von Brese-Winiary, were promptly ordered for Konigsberg. Construction began in 1843 and took 16 years to complete.

The new defences were largely built on the remains of the First Defensive Ring, eventually surrounding the city with an 11 kilometre belt.
The completed fortifications contained eight gates (three to the south, five to the north), which had been artistically designed by Friedrich August Stuler and Wilhelm Sturmer in a Tudor style using brick and yellow sandstone. Even before their completion though the new fortifications were already becoming obsolete due to advances in artillery and in the early twentieth century, some walls and gates, specifically Steindamm and Tragheim gates, in the north-west part of the city were dismantled to ‘soften’ the landscape and to improve communications.