Sant'Anna dei Palafrenieri is a church dedicated to St Anne, mother of the Blessed Virgin Mary. The official title is Sant'Anna in Vaticano. This is the parish church of the Vatican City located at the Porta S. Anna, the commercial entrance to the Vatican (the Palafrenieri are the traditional noblemen grooms of the popes and éardinals). The church is open to the general public.
For reference, a plan of the church is available
here.
Construction started in 1565, under Pope Pius IV, but it was only in 1572 that the process
started in earnest. The architect was
Jacopo Barocci da Vignola; after his death in 1573
his son Giacinto Barozzi took over.
The building was funded by the Confraternity of the Palafrenieri (Palafrenieri is just a pompous word for grooms),
which was founded in 1378 by
Pope Urban VI as part of the Papal court.
It was given a baroque flavor by
Alessandro Specchi who (in the early 18th century) added the
portal, the balustrade and the bell towers. The modern entrance to the Vatican was built under
Pius XI, whose heraldic symbols (an eagle on top of three pills) are sculpted in "lictorial" style
on top of the pillars ("lictorial" is called the style prevailing in the late 1930s in Italy).
Today it is the parish church of the Vatican and its official cemetery. It is served by Augustinian friars.