The tract of the
walls, called Aurelian after the emperor who had them
built between 271 and 275AD., covered the oldest
republican and suburban city wall like the one over the
Tiber. The structure in brickwork - with external
quadrangular towers about every thirty metres - extended
for almost 19 kilometres along which the most important
gates opened (some rebuilt in modern times) and minor
openings (posterulae). Reinforced by Massenzio, they
were completely rebuilt first by Honorius, who doubled
the height, then by' Belisarius, with added backs, like
those of Sangallo.
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Violated by Alari-. cus in 410,
the tract of the walls near Porta Pia was the theatre of the
i historic "breach" into which the Italian army penetrated
on 20th Sep-' tember, 1870. The Museum of the Walls, in the
St. Sebastian Gate,
documents the story of the ancient defensive structure.It
was called Porta Pia in honour of Pius IV who, in
replacement of the ancient Nomentana Gate, imposed the
opening to connect, by way of the new urban straight stretch
of the Strada Pia, the pontifical palace of Monte Cavallo (Quirinal)
to the outof-town basilica of Sant'Agnese.
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The project, already drawn up in
January, was almost certainly given to Michelangelo on the
2nd July 1561, although it had already been started on some
months before. The external portal, on Michelangelo's
design, was probably constructed byVirgilio Vespignani,
author, in 1853, of the complete re-working of the attic
which had, perhaps, fallen at the end of the century,
crowned by the triangular pediment. |
