Iru (Iru) 
Inn, hill and probably one-time village on the NE border of Tallinn, or the one-time standing boulder at ///zing.engaging.embodying, Iru Ämm, Iru’s mother-in-law or the Old Woman of Iru, into which Linda – Kalevipoeg’s mother, having been abducted and possibly raped by a Finnish sorcerer – was turned by Pikker’s lightning (see Pikri). Ironically, the original boulder was destroyed in the mid 19th C during a bonfire party. It was subsequently broken up and used to build, according to version, the Iru bridge (Irusilla) in 1865-67, or a Russian military airfield during WWI. Now replaced by a statue. Also site of a pre-Bronze age (±3000 BP) Corded-ware settlement.
Kalamaja (Kalamaja)
Fisherman’s hut, name of a one-time fishing village, along with the three ages of man: Uus-Kalamaja (new, but let’s say ‘young’ for poetic licence), Kesk-Kalamaja (Middle-aged), and Vana-Kalamaja (Old). The word maja, probably first meant a temporary shelter, hut or stopover, as suggested by its neighbouring Izhorian, Karelian, Ludian and, to a lesser extent Finnish, Livonian and Votic. Records date back to 1374 and known as Suddenpe in 1421, prob. MLG+Old Est. for “On the marsh/swamp” (südde/sudde = morass or swamp) + pe>pea (see Narva). Note, too the old ‑n genitive.
Kelmiküla (Kelmiküla):
Rogue’s village, scampstown (a slum in the late 19th C). Also name of story by Kitzbergi A. about life in Viljandi. Why it got that name is uncertain. It can’t be because it’s on the wrong side of the tracks, because it’s on both... There are, of course, legends, which are, precisely, legends... The story goes something like this: Kelmiküla is next to Pelgulinn of Sherwood Forest status, so this is where the bad guys went. My suspicion leads me elsewhere: a name is often given for reasons of singularity, and running from the law has never been that special, unless you happen to be the runner yourself. What would strike one, however, would be the numerous chimney-stacks associated with the brick and tile industry of the (spreading?) Kopli area, and MHG kamīn, kemīn, deriving from Greek κάμινος (kámínos) for chimney, fireplace, hearth, furnace, oven, or brick kiln, could easily shift from kemīn to kēlmi. But, as always, could be wrong :o) All the more so since Kelmiküla is quite a common place name in Estonia. Suggestions?...
Kassisaba (Kassisaba)
The name of the district is often accused of coming from the German military term Katze for an elevated bastion (none found), and the road leading from it as its tail (Ger. Schwanz, which also means ‘dick’). This is almost certainly wrong. A) Ger. Katze has a multitude of meanings and no self-respecting army would name or nickname one of its defensive structures after a vagina, trollop, flighty woman or prostitute, no matter how cute and cuddly its primary definition; and B) Estonia has had at least half a dozen farms or bits of village called Kassisaba anyway, hardly fighting stuff, especially the flower of that name: spiked speedwell, Veronica spicata. It is almost certainly a legacy misrecollection of Ger. Schanze, ‘sconce’ in English, which is indeed an elevated fortification (such as a redoubt), often protected by a couvreface, but a term so rarely used that even Tristam Shandy’ Uncle Toby failed to mention it once… As to the ‘tail’, the point of a bastion is to avoid having a road either to it or from it, so my suggestion is a bilingual mistranslation, with Schanze sounding like Schwanz (tail), and Katze, a possibly humorous or intentional misreading of Est. Kaitse (defence)’, so just a plain old defensive bastion. Part of Paldiski maantee was once known as kassi sabba.