The Street of Seven Stars by Mary Roberts Rinehart

Published in 1914, this novel tells the story of Harmony Wells, an innocent and beautiful American in Austria to study violin. Harmony has talent and she dreams of a career in music. After her friends run out of money and return to the States, Harmony stays on in hopes of earning enough money to continue her lessons. Along the way, she meets Peter Byrne, an American doctor in Vienna following his dream to study surgery. Peter is already watching over an orphan boy in a local hospital and now he takes it upon himself to protect young Harmony from the unsavory side of life in the big city. With life pressing in, Peter and Harmony each must decide how much to sacrifice for the sake of their dreams - and for each other.