New Elfsborg Fortress, Sea fort on Kyrkogårdsholmen, Gothenburg, Sweden

New Älvsborg is a sea fort on Kyrkogårdsholmen, a small rocky island at the mouth of the Göta River in Gothenburg. It was built on what were originally two separate islets, the southern one holding the fort itself and the northern one a hornwork; the narrow channel between them served for a time as a boat harbour and survived until at least 1820. Grey and tan stone walls with angular bastions enclose grassy courtyards, a tall square tower with a steep red-tiled pyramidal roof, lower red-roofed buildings and a long red-roofed range. A narrow stone and concrete causeway crosses the water to the island.

Construction began in 1653 after Axel Oxenstierna's government approved plans for a fortress on Kyrkogårdsholmen, replacing the outdated Old Älvsborg. Progress was slow due to bad weather and lack of money, and the fortifications were only officially completed in 1677, during the Scanian War. In 1660 Old Älvsborg was decommissioned and its equipment, including chapel bells and pulpit, was moved here.

The fortress displays original 17th-century Swedish military architecture through its buildings and layout that visitors can explore directly. Walking through the commandant's residence, soldiers' quarters, and fortifications gives a sense of how military life was organized and structured at this outpost.

Access is by boat from Lilla Bommen harbor in Gothenburg, with tours available between May and September. Visitors should wear sturdy shoes since paths on the island are uneven and the wind over the water can be cool.

On 19–20 July 1719 Tordenskjold assembled seven ships of the line, two frigates, four galleys, three floating batteries and four barges to storm the fort, whose garrison of about 360 men under Johan Abraham Lillie included two companies of the Älvsborg Regiment, a Saxon infantry company and the artillery detachment. The assault failed, and Nya Älvsborg was besieged but never taken by an enemy force.