Cordilheira translates to "mountain range". It's a striking and somewhat unexpected word in the context of urban exploration.
Caetano Veloso uses it poetically to suggest that even beneath the city's asphalt, there's a hidden, majestic landscape—"Há uma cordilheira sob o asfalto" (There's a mountain range under the asphalt). This creates a vivid image of depth and hidden grandeur, making it a memorable and thought-provoking word.
The song opens as an invitation to stroll — "Vamos passear na floresta escondida, meu amor" (Let's take a walk in the hidden forest, my love) — and then keeps finding that the walk cannot happen in the open. "Há uma cordilheira sob o asfalto" (There's a mountain range under the asphalt): the route runs beneath the city, where the Mangueira samba school "Passa por debaixo da Avenida Presidente Vargas" (Passes underneath President Vargas Avenue) instead of parading down it. Even the destination has to be reached in secret — "Vamos passear nos Estados Unidos do Brasil" (Let's take a walk in the United States of Brazil), the country's old official name, but only if "Vamos passear escondidos" (Let's walk hidden).
The last third is one long descent, each line naming what the walkers pass beneath: "Debaixo das bombas, das bandeiras" (Under the bombs, the flags), "Debaixo das botas" (Under the boots), "Debaixo das rosas, dos jardins" (Under the roses, the gardens), "Debaixo da lama" (Under the mud). It stops at the last place left to hide, repeated over and over until the recording fades out: "Debaixo da cama" (Under the bed). Recorded in 1968, the year Brazil's military government shut down public life, the walk that began as a date ends as somewhere to lie still.