Here are a few Crimean examples, to set the scene:
This is Sevastopol' Town Post sub-office, one of two postmarks I know from that place and definitely the oddest. I found it in Bristol while visiting Ian Baillie.
A nice registered cover from Simferopol' Town Post sub-office, serial letter "a", but the same serial letter was also used for a smaller postmark:
Incidentally, under that British registration label is a Russian label identical to the label on the other cover.
What brought all this on? Well, eBay spat out this:
A nice old postmark of Odessa's second Town Post sub-office. First time I've seen one, although Odessa specialists may have done better.
But you see the problem here...Town Post postmarks are like landmines for postmark collectors: you don't know where they are and how many there are. But they're very nice to find!