The main façade of the church faces onto the Via del Quirinale (formerly the Via Pia), as does Borromini's San Carlo alle Quattro Fontane further down the road.

Unlike San Carlo, Sant’Andrea is set back from the street and the space outside the church is enclosed by low curved quadrant walls.

The oval form of the main congregational space of the church is defined by the wall, pilasters and entablature, which frame the side chapels, and the golden dome above.

In contrast to the dark side chapels, the high altar niche is well lit from a hidden source and becomes the main visual focus of the lower part of the interior.

As a result, the congregation effectively become ‘witnesses’ to the theatrical narrative of St Andrew which begins in the High Altar chapel and culminates in the dome.

Bernini combined painting, sculpture and architecture into a synthesis to create visually the idea of the apotheosis of St Andrew in this spiritual theater.

He used a similar synthesis of artistic modes in his design of the Ecstasy of Saint Theresa in the Cornaro Chapel of Santa Maria della Vittoria.

It houses the tomb of King Charles Emmanuel IV of Sardinia and Piedmont, who abdicated in 1815 to enter the Society of Jesus and then lived in the Jesuit novitiate, adjacent to the church, until his death in 1819.