Find a train to the Hall of Heroes is a mission in Ratchet & Clank taking place in Aleero City on planet Kerwan. After Cora Veralux advised Ratchet and Clank to meet Al in his roboshack to upgrade Clank on their way back to the Hall of Heroes, Al advised the two to board a grav-train nearby to take them straight back there to begin training with Brax Lectrus. With the newly installed Helipack, they were able to traverse the city more easily.
With the Helipack equipped, use the vendor in Al's roboshack to restock on ammo and purchase any available Raritanium upgrades before moving past his roboshack. Use the Helipack's boost jump with while stationary to boost up to the top of the stack of crates. At the top, use while running to stretch jump across to the roof of the building in front, then use the elevator to be taken higher up to a higher roof. Once here, head left to a brown edge, directing you to another building with robomutts and blarg troopers on top.
Jump and hold in the air to glide using the Helipack and reach it, then kill the enemies (easily defeated by using the Proton Drum and/or Fusion Grenade). Ride the next elevator to the top, and follow the linear path from here to entrance to the grav-train station, found in a tunnel with steps leading upwards inside, defeating the robomutts, blarg troopers, and blarg commanders along the way.
When entering the grav-train station, the mission "Ride the train to the Hall of Heroes" will commence.