Dinah tails Councilwoman Pollard and spots the Vigilante waiting on the fire escape outside her apartment in episode 6x05 “Deathstroke Returns”.
Dinah catches a glint from the sniper's scope in the window and later Felicity & Curtis review footage of him leaving in episode 6x05 “Deathstroke Returns”.
Todd wakes up to find his landlord smashing up his car and then realizes he has locked himself out of his apartment, things go downhill from there in episode 1x01 “Horizons”. Farah shows up at the building to rescue Lydia Spring in a flashback in episode 1x02 “Lost & Found”. Dirk is confronted by Col. Riggins in the lobby in episode 1x03 “Rogue Wall Enthusiasts”.
The replaced Agent Weedle watches the building.
Amanda heads off with the Rowdy Three.
Todd arrives home to tell Amanda about his lies and gets attacked by the bald men.
Webb lives in his building across the years.
Source: YVRShoots — Twitter, 2