Most sources report that poets Nikolai Gumilyov and Maximilian Voloshin dueled over the infamous Cherubina de Gabriak near where Alexander Pushkin was killed in a duel (which is located here).  But precise coordinates may be needed.

Cherubina de Gabriak

Cherubina de Gabriak (Russian: Черу́бина де Габриа́к; IPA: [t͡ɕɪˈrubʲɪnə dʲɪ ɡəbrʲɪˈak] ( listen)) was a literary pseudonym of Elisaveta Ivanovna Dmitrieva (Russian: Елизаве́та Ива́новна Дми́триева; IPA: [jɪlʲɪzɐˈvʲetə ɪˈvanəvnə ˈdmʲitrʲɪjɪvə] ( listen); March 31, 1887 – December 5, 1928), possibly together with Maximilian Voloshin.

• http://en.wikipedia.org/wiki/Cherubina de Gabriak