Palazzo Altemps and Castel Sant'Angelo, Privately

Two buildings, one of which almost nobody visits. Palazzo Altemps stands a minute from Piazza Navona and holds part of the Museo Nazionale Romano. It is a frescoed Renaissance palace with ancient sculpture arranged through its rooms, and on an August afternoon you can have whole galleries to yourself while the queue outside the Pantheon runs down the street. Roman marble displayed in a private palace rather than a museum hall is a different experience: the pieces stand in rooms built for living in, at the height they were meant to be seen from. From there the tour crosses to Castel Sant'Angelo, which is the opposite kind of building. Hadrian's mausoleum, fortified and rebuilt by every century that had a use for it, until the tomb disappeared inside a castle. A private guide holds the two together, which is the point: the same city, the same centuries, one collection kept indoors and one building that had to survive outdoors. Bring a camera. The guide meets you at Palazzo Altemps, not at the castle.