This is the technical difference between lay and lie:
You lay an object onto a surface.
Could you lay those mats on the floor, please?
She laid the books on the table.
The workers are laying the carpet in the new building.
Again, you lay an object onto a surface. But a person/thing lies (itself) on the surface:
There was a package lying on my doorstep.
The clothes are lying all over the floor.
For a person, to lie + a preposition of place means to put yourself horizontally on a surface:
I'm feeling sick. I need to lie down.
She's lying on a towel on the beach.
Now... to complicate matters - the past tense of lie is lay!
Present Continuous Past Past Participle
LAY LAYING LAID LAID
LIE LYING LAY LAIN
Also, native English speakers often say "I need to lay down" and "She's laying on a towel on the beach." - even though it's incorrect!
You lay an object on a surface.
We laid the flowers on the grave.
You lie (yourself) on a surface.
He's just lying there on the couch watching TV.
An object lies on a surface.
There was an abandoned bicycle lying on the sidewalk.
This lesson refers to the meaning of "lie" as an object lying on a surface. There's another meaning for "lie": to say something that isn't true. In this case, the past and past participle would be lied and lied:
The little boy ate the cookies, then lied and said his sister had eaten them.
The main attraction in Graz is the Schlossberg (Clock Tower). It stands proud and is visible from all points in the city. Tourists and local visitors need to climb to the top to see the fabulous view of Graz and the surrounding area. The Schlossberg Stairs are located at the far end of Schlossbergplatz.The impressive stairs are cut into the rockface of the Schlossberg Hill and doubles back and forth up to the top of the hill and clock tower. Great views over the city can be enjoyed during the climb up the steps. The 260 steps of the stairs are a much more enjoyable (although tiring!) way to reach the top of the Schlossberg. For the less energetic, you can take the Schlossbergbahn or lift.