Police were called after a teenager was spotted dangling his legs over the top of a Worthing multi-storey car park on Tuesday evening.
A passing motorist, who said he feared for the person’s life, alerted officers to the incident atop the Grafton car park on the seafront shortly after 8pm.
The witness said: “My heart was in my mouth. I genuinely feared the worst.
“To put yourself in such danger is just madness.
“It reminded me of people who get too close to the cliff edge at Beachy Head. I just hope he was okay.”
The witness said the teenager, dressed in a black sweat shirt, dark jeans and a grey beanie hat, climbed over railings to sit on the edge of the precipice.
He remained there for at least ten minutes while nervous promenaders looked on, they said.
A Sussex Police spokesman said: “At 8.16pm on Tuesday, police were called following concerns for a man reported to be the wrong side of the railings on top of Grafton Car Park, in Augusta Place, Worthing.
“Officers attended and there was no trace of the man.”
The Grafton car park is one of several key sites which Worthing Borough Council wants to see redeveloped in the long term, with officers hinting last year they could seek its demolition.