The Lower Embassies
An opulent demonic building and an impressive devilish barracks face each other across the street. Their staff attempt to recruit tieflings to one side or the other of the Blood War - "honour your fiendish ancestry!" etc. Bloodthirsty/foolish/desperate tieflings can earn generous fees by enlisting... though most are wise enough to stay away, so the fiends seize the opportunity to give recruitment speeches to non-tiefling visitors to the district.

The Massage Parlour
Tieflings of succubus/incubus descent offer their specialised services in this ornate parlour.

The Guild
This abandoned warehouse covers sewer tunnels housing the city's Thieves Guild, comprised of many different races but led by a tiefling rogue.

The Shops
A series of small, disreputable shops selling antiques, curios, potions, books etc, all imbued with black magic from the Abyssal and Infernal planes.

The Penitents
A religious society of tieflings who wish to purge themselves of evil. They cut off their horns and tails, wear rags stained with their own blood, and indulge in ritual self-flagellation & wailing prayers during group processions through the district. Most tieflings (even good-aligned ones) regard them with some degree of contempt.

The Ambassadresses
A covey of night hags in humanoid form, these three sisters own one of the Shops and represent the neutral fiendish interests in the district. They have ties to organised crime in the district and keep the peace when the Lower Embassies try to start up trouble (or at least when they would threaten the hags' income).