An angel sent Philip to the desert road that goes from Jerusalem to which city?

Answer: Gaza

On the road from Jerusalem to Gaza, Philip met an Ethiopian eunuch returning from worship in Jerusalem.

“Now an angel of the Lord said to Philip, “Get up and go south to the desert road that goes down from Jerusalem to Gaza.” So he started out, and on his way he met an Ethiopian eunuch, a court official in charge of the entire treasury of Candace, queen of the Ethiopians. He had gone to Jerusalem to worship,”— Acts 8:26-27 (BSB)