jats:pDuring a pre‐site survey and construction of a new metro route and station in Copenhagen, fossiliferous organic‐rich sediments were encountered. This paper reports on multidisciplinary investigations of these organic sediments, which occurred beneath a sediment succession with a lower till, glacifluvial sand and gravel, an upper till and glacifluvial sand. The organic sediments were underlain by glacifluvial sand and gravel. The organic‐rich sediments, which were up to 0.5 m thick, accumulated in a low‐energy environment, possibly an oxbow lake. They were rich in plant fossils, which included warmth‐demanding trees and other species, such as jats:italicNajas minor</jats:italic>, indicating slightly higher summer temperatures than at present. Freshwater shells were also frequent. jats:italicBithynia</jats:italic> opercula allowed the sediments to be put into an aminostratigraphical framework. The amino acid racemization (<jats:styled-content style="fixed-case">AAR</jats:styled-content>) ratios indicate that the organic sediments formed during Marine Isotope Stage 7 (<jats:styled-content style="fixed-case">MIS</jats:styled-content> 7), which is consistent with optically stimulated luminescence dating that gave ages of 206 and 248 ka from the underlying minerogenic deposit. The assemblages from Trianglen are similar to interglacial deposits from the former Free Port (1.4 km away) in Copenhagen, except that jats:italicCorbicula</jats:italic> and jats:italicPisidium clessini</jats:italic> were not found at Trianglen. The presence of these bivalves at the Free Port and the ostracod jats:italicScottia tumida</jats:italic> at Trianglen indicates a pre‐Eemian age. <jats:styled-content style="fixed-case">AAR</jats:styled-content> data from archived jats:italicBithynia</jats:italic> opercula from the Free Port were almost identical to those from Trianglen, indicating that the two sites are contemporary. We suggest the Trianglen interglacial be used as a local name for the <jats:styled-content style="fixed-case">MIS</jats:styled-content> 7 interglacial deposits in Copenhagen. <jats:styled-content style="fixed-case">MIS</jats:styled-content> 7 deposits have rarely been documented from the region, but <jats:styled-content style="fixed-case">MIS</jats:styled-content> 7 deposits may have been mistaken for other ages. The use of <jats:styled-content style="fixed-case">AAR</jats:styled-content> ratios in jats:italicBithynia</jats:italic> opercula has a great potential for correlation of interglacial non‐marine deposits in mainland northern Europe.</jats:p>