Piazza Navona is famous as a Baroque composition, yet its long straight sides and curved northern end were fixed by the Stadium of Domitian. Houses, churches and palaces grew over the seating while the competition floor became a public street and, finally, a square. The ancient building survives both underground and at the scale of the modern city.
In the seventeenth century the Pamphilj family made this inherited outline into a theatre of papal power. Palace, church, fountains and obelisk were coordinated across the piazza without becoming one architect's single design. A short walk south leads to Pasquino, Campo de’ Fiori and the Cancelleria, where satire, commerce, punishment and institutional authority occupied neighbouring spaces.
Palazzo Altemps closes the route by changing the question from survival to collecting. Ancient marbles there are not displayed against neutral walls: they inhabit a Renaissance residence shaped for antiquities, later restored as a museum. This guide separates original remains from later settings, documented history from popular legend and publicly visible façades from interiors whose access must be checked in advance.
From arena to piazza and from fragment to collection, the route is built from reused space.