The other thing Keyser needs to keep in mind is that his stay is on Christmas Day (aka, arriving Xmas Day & departing the next morning). There may not be much open on Xmas. Having said that Google says that Russia (Orthodox) actually celebrates Xmas/public holiday on Jan 7, so it might not be a problem. It's just Catholic & protestant churches that celebrate on Dec 25th & 12/25 is not a public holiday in Russia.

Cheers.