The 3-storey, horseshoe-shaped Grolman Bastion was built opposite the Kronprinz Barracks (to which it is connected by means of an underground tunnel) in 1851 and is named after key Prussian general General Karl von Grolman who had died 8 years before. Its strong defensive capabilities were recognised by the Germans in 1945 and it served as the 367th Infantry Division command position during the storming of Königsberg. As with the neighbouring barracks, it is sadly not open to the public. 

You can however head through the yard where there appears to be a mechanics garage and clamber up and onto the top of the huge earth bank which formed the first part of the fortifications. With a moat in from and fortifications built on top, these eat facing defences must have formed quite a challenge for the attacking Red Army. At one point you will find a part of the bank and wall breached and it is possible, with a lot of care, to carefully climb down on the moatside path below. It is from there that you'll get a full appreciation of how daunting these fortifications, with their gun positions and, apparently, camera positions to warn of mine attack must have been and the loss of live involved in taking them. Although there is less to see as there is nothing open to the public, the Grolman bastion is of interest because of the range of defences included at this one point.