The phrase "across a hill" is correct and usable in written English.
It can be used to describe movement or location in relation to a hill, often indicating a position on the opposite side or traversing over it.
Example: "We walked across a hill to reach the beautiful valley on the other side."
Alternatives: "over a hill" or "beyond a hill".
Stairs and walkways cut across a hill, connecting cabins.
He gestures across a hill to the gray-stoned Belvedere.
With over 100,000 higgledy-piggledy crosses across a hill, this is an imposing and sinister sight.
At the eastern tip of the Israeli settlement of Ariel, cranes and earth-movers are at work on the college campus, which stretches across a hill overlooking the villages and valleys of the West Bank.
The British military cars, tin lizzies carrying men in the open, are almost comically antique and vulnerable; the I.R.A. rebels, who wear awkward long coats and caps as they scramble across a hill, look less like a guerrilla force than like fellows who had planned to go shopping with their families but somehow got sidetracked into a bizarre adventure.
Still, the vehicular combat itself ties directly into the increased level of destructibility that now lies in every single part of Battlefield 1. There's a real adrenaline rush to pushing across a hill with a dozen squad mates, all of you charging forward as the rain batters against the sludgy mud of the Argonne Forest.
We headed off, across campus, down a hill and to the Delaware & Raritan Canal.
If the game comes across a little like Silent Hill, that's because the characters were designed Takayoshi Sato, that series' character designer.
The path led up a hill, across a stream, back across the stream, and past the carcass of a sheep, which looked deflated, like a lost balloon.
The fresh grave sits on a hill across from campus.
On the slope of a hill across the valley another huddle of gravestones has sprung up.
