Okay, so imagine you have a treasure box that you want to hide somewhere in your house. You don't want anyone else to find it, so you have to choose a really good hiding spot. This is kind of like what ancient Greeks did with their important things, except their treasure box was actually a burial urn, and their hiding spot was a place called Phourni.
Phourni was a special place where they buried important people, kind of like a graveyard. But instead of burying them in the ground, they put them in big jars called urns, and then they put the urns in special rooms that were underground. These rooms were really hard to find, so people wouldn't disturb the urns and the things that were buried with them.
But even though they were buried deep underground, people could still visit the urns and leave offerings for the people inside. They would use little tunnels and stairs to get to the rooms where the urns were hidden. And they would bring things like food, wine, and jewelry to honor and respect the people who had been buried there.
So basically, Phourni was a secret hiding spot for really important people in ancient Greece. And even though it was hard to find, people still knew about it and would visit the urns to honor the dead.