Brunelleschi's most pure architecture can be seen in the interior of the Pazzi Chapel which adjoins Sta. Croce.
Built beginning ca 1440, and commissioned by the prestigious Pazzi family, the Pazzi Chapel is a good example of Brunelleschi's use of "pietra serena"
(the gray or 'quiet' stone) ,that acts as an outline of architectural elements that show his use of pure geometric proportions.
A sense of scale can be seen by including someone in the image, in this case me !

The Pazzi Chapel, can be entered via the south transept door in Sta. Croce, or from the street.