Grant tracks the mysterious people to an abandoned building where Jeff is searching for Carly in episode 1x01 "Travelers". Grant explains his presence to the cops and receives a package from another Traveler in episode 1x02 "Protocol 6".
Peyton hears a noise while working late at night and searches the halls for it in episode 2x06 "Max Wager".
Lobby & stairwell of the apartment building that the Fringe team investigates throughout episode #314 "6B".
A sniper fires on the Fringe team in an attempt to kill the shapeshifter from the top of this building in episode 4x17 "Everything in Its Right Place".
Rebecca searches this building's rooftop and locates Ernest Cobb before he can kill again in episode 1x02 "Ernest Cobb".