Input (grade 7): Bernini's first work at St. Peter's was to design the baldacchino, a pavilion-like structure tall and claimed to be the largest piece of bronze in the world, which stands beneath the dome and above the altar.
Output (grade 6): Baldacchino and niches Bernini's first work at St. Peter's was to design the "baldacchino" which is like a tent or "pavilion" above the High Altar.