LIMA — Peruvians call the cliffs above the highway that dumps Lima into the Pacific La Costa Verde — the green coast — even though there’s barely any green left. When the surfers down below look up at the city, they mainly see towering erosion walls of deep brown earth, forbidding reminders that just beyond the crests are 7 million people and taxis that never stop honking. Built into one swath of hillside is an urban warning to the waves — a three-story outdoor mall where you can buy Incan wool sweaters and then eat at a Tony Roma’s. It’s a testament to the bumpy drive toward modernity that Lima’s been pursuing since 1990, a pursuit that has filled this city overflowing with migrants from the Andean provinces, and with 24-hour Shell stations, Burger King, and KFC delivery boys on sputtering mopeds.

During the winter months, Lima is — as Peruvian writer Mario Vargas Llosa describes it at the beginning of his just published Letters to a Young Novelist (Farrar Straus Giroux) — "gray Lima." It’s the only reference Vargas Llosa’s home town gets in the book, and it leaves an image of Lima as a city of cold cement streets wrapped in blankets of never-lifting fog. The gray of the city clouds its true colors, though: 24 districts where Peruvians of European descent (Criollos) clash with Indios (Indians) and buildings jump colonial centuries in muted yellows and aqua blues.

The 19th century weighs heaviest on Barranco, Lima’s after-hours district of choice, where the history of Peruvian music — from traditional huayno (the pan-flute-based highlands music of Peru) to the techno-cumbia contemporary dance-floor take on traditional Colombian music — pours out of crumbling bars steeped in bohemian romance. I’m sitting in one of them with Gian Marco, Lima’s local pop hero and the Latin world’s most in-demand new composer, who every Friday night for the better part of the ’90s, in a bar just around the corner, sat on a stool with his acoustic guitar and sang for the customers while they drank their Pisco Peruvian liquor and bottles of Cusqueña beer. Now he plays to sold-out crowds of 30,000, and when he walks through Barranco, young Peruvian girls cup their mouths to stop from screaming.

After five albums in Latin America and a stint as a host on a kids’ game show, Marco has moved to Miami and released the Emilio Estefan–produced A Tiempo ("In Time"; Crescent Moon), his first go at US audiences. Marco is that rare member of the Latin pop world who can balance his roots with the commercial demands of a global market. He has written songs for Mandy Moore and Marc Anthony, yet he remains a deferential student of Peruvian music, dabbling in Afro-Peruvian styles and Peruified nueva trova (the Latin American "new song" folk movement) and even releasing an album of classic waltz-tinged, European-based música criolla. A Tiempo is the perfect offspring of the Lima-Miami mix, a sparkling showcase of tropicalized Latin pop balladry that reflects his understanding that before you can go global, you have to come from somewhere.

The album’s radio-ready hit "Se Me Olvidó" ("I Forgot") is also its most secretly Peruvian song, a sunny broken-heart diatribe built atop the rhythms of a cajón — the wooden box that’s the percussive building block of Afro-Peruvian music. And the cajón is all over Espíritu Vivo ("Living Spirit"; Luaka Bop), the latest from the great Afro-Peruvian singer Susana Baca, whose world is centered far from Barranco in Chorillos, a black neighborhood on the outskirts of Lima. Although Espíritu is more avowedly Peruvian in style than A Tiempo, Baca is also interested in interpreting local music through global idioms, so her warm, elegant voice graces songs by Johnny Mercer, Björk, and Caetano Veloso alongside those by Peruvian composers Chabuca Grande and Mario Lazo. Peruvian musicians are also on board, as are downtown New York favorites John Medeski and Marc Ribot.

Before he killed himself in Lima in 1969, the Peruvian novelist José María Arguedas wrote that Peru consists of two nations, the Quechua (the indigenous people of Peru) and the Criollo. Espíritu Vivo furthers Baca’s attempt to prove that there is an invisible third — the black nation descended from African slaves brought to Peru by Spanish and Portuguese colonists. For Arguedas, Peru’s ethnic nations were "walled-in," separated by borders he was determined to break down without losing his Indian identity. On Espíritu, Baca breaks down borders between genres and traditions without ever relinquishing her blackness.

With his Italian parents (a father who’s a famous singer, a mother who’s a famous actress), Gian Marco comes from the nation both Baca and Arguedas position themselves against. So his task has been a different one: how to open international pop up to Afro-Peru, how to create a conversation between Miami and the sounds of traditional Peruvian instruments like the charango and the quena that Arguedas held so sacred (in them, he once wrote, "I shall hear everything"). Marco may represent what Arguedas vowed never to become — an export of acculturated Peru — but A Tiempo chips away at Peru’s national walls in its own way, from the top down, bringing the many colors of the gray city to a world that has never heard it before.