Beyond the Ruins is the 6th chapter in Chrono Trigger. This is where Crono jumps into the future for the first time and meets Robo. This is also where he finds out about Lavos and the destruction to the planet.
After Crono, Marle and Lucca escape the guards at Guardia Castle in 1000 A.D., they stumble upon a Time Gate which sends them into the future, 2300 A.D. Now finding themselves in this strange new post-apocalyptic world, they try to find a way home. While talking to the locals, they find out they are in the distant future.
After appearing in Bangor Dome and paying a visit to Trann Dome, Crono and his party travel through Lab 16 battling strange creatures. They come across people living in Arris Dome and try to help them by battling the Guardian robot and it's Bits. When they find that the refrigeration unit had failed, they discover a corpse holding a seed. Crono hands the seed over to the people of Arris Dome and the man named Doan agrees to plant it in hopes that it will grow in their devastated world.
While searching the inner-workings of Arris Dome, they discover a large computer in the Info Center. It's within that computer's database that they find out an entity called Lavos destroyed the planet back in 1999 A.D. That's when Crono and his friends decided to go back in time and battle Lavos to save their future.
Using the computer, Lucca ran a search on time warps. The results informed them that there was a Time Gate on the eastern continent in Proto Dome. Doan gives them the Bike Key so they can use the Jet Bike in Lab 32. So Crono and his party leave Arris Dome and venture east. When they arrive in Lab 32, Johnny challenges Crono to a race. Using the Jet Bike, Crono races him along the highway through the ruins and beats him. Having reached the other end of Lab 32, Crono and his party continue on their journey.
They soon reach Proto Dome, but find the inner chambers locked. Lucca also repairs a deactivated robot they find in the Dome. When switched on, the robot says his serial number is R66-Y, but Crono renames him Robo. Thankful for the repairs, Robo agrees to head into the Factory up north to turn on the power so they can open the door to the inner chamber to get to the Time Gate. But one of them has to stay behind to open the door because the power won't stay on for long. So Crono chooses whether Marle or Lucca stays, and the party of three heads north to the Factory.