For us locals, it's quite interesting that Rachmaninoff stayed in Copenhagen for almost a year from January 1918, while also doing tours in Scandinavia.
Danish Wiki has some information about it; one might use Google Translate
https://da.wikipedia.org/wiki/Sergej_RachmaninovRachmaninoff was staying in the upscale, northern Charlottenlund area, in Ingeborgvej street, paying rent at a Lieutenant Jering's place and borrowing his piano. His daughters would frequent the local school, and the music editor Wilhelm Hansen helped him organize practical and musical matters and concerts.
Later, he stayed at Skovvej near Jægersborg Alle street, in the same area. But then the Spanish Flu came and prevented any further official arrangements, making him decide to go to the US in November 1918.