The railway that ran from Massawa on the Red Sea coast up through the highlands toward Keren was the spine of Italian colonial infrastructure in Eritrea, and it was central to the 1941 battle. The Italian defenders used the railway pass north of Keren as their main defensive position, and when the line finally broke they destroyed the pass themselves to slow the British advance. The ruins of that infrastructure — retaining walls, embankments, the remnants of fortifications built into the hillsides — are still visible around the city for anyone who goes looking.
This is not a formal museum or a signposted site. It is more like a layer of history that sits on top of the landscape if you know to look for it. Locals can point you toward the most visible remnants; asking at your hotel or at a cafe near the market is the best starting point. For anyone with an interest in military engineering or colonial infrastructure, the combination of the railway works and the fortifications built around them is genuinely interesting — a physical record of how two armies fought over a single mountain pass for nearly two months.