Rome at two in the afternoon in August is a closed city. The shutters are down, the bars are slow, the fountains hold small clusters of teenagers who have nowhere else to be cool. The advantage of being in the centro storico at this hour is that it was built for it. The Pantheon’s portico is sixteen Egyptian granite columns and a roof — the same roof Hadrian put up in 126 AD — and the temperature under it is meaningfully lower than the temperature in the piazza in front. From there the trick is to chain similar covers: the loggia of Palazzo Madama, the deep northern shadow of the Palazzo Altemps, the arched arcade along the back of Piazza Navona, the porticos of the Borromini and Bernini churches that step the route every hundred meters or so.
The picks below string those together. They are short — the centro storico is small — and they are slow. The premise is that you are not trying to get anywhere faster than the heat lets you. Each pick ends at a covered place where you can sit for fifteen minutes: a church nave, a wine bar with a barrel ceiling, a bookstore on a cool stone floor. Stay Cool treats the church naves as buildings (they are; they belong to the Vatican) and routes you through their cool dim middles when the geometry calls for it. We do not route through services; the app checks.
A small note on the cobbles. The sampietrini, the basalt cubes that pave the centro, store the day’s heat and release it overnight. By 4 PM you can feel them through thin shoes. They are also slick when wet, which they will not be in August. The galleries listed below are mostly travertine and tile; cooler underfoot.