On the north side the square is dominated by the
Porta
del Popolo, which leads to the Via Flaminia.
Since the Via Flaminia was built in AD

220 to connect
Rome with the Adriatic coast, many travellers entered
the Rome via the square.
In 1562 Pope Pius IV Medici commissioned architect Nanni
di Baccio Bigio to construct a large gate, the Porta
Flaminia, to impress the pelgrims who entered the city
via the Via Flaminia. In 1655, on the occasion

of Queen Christina of Sweden's arrival in Rome, the inside
of the gate was decorated by Bernini on Pope Alexander
VII Chigi's request. The gate was later renamed Porta
del Popolo.
In 1589, Pope Sixtus V had an Egyptian
obelisk moved from the
Circus Maximus to the
center of the square. The 23,2m/73ft high obelisk was
originally built in 1300 BC and was taken from the
Sun Temple in Heliopolis in 10 BC by the Roman Emperor
Augustus. The obelisk was erected at the
Circus Maximus to commemorate the conquest of Egypt.
In 1815 to 1816 Giuseppe Valadier redesigned the square
by adding th

e
walls around the square, giving the square its current
oval shape. He also added the central fountain and the
four Egyptian lions around the obelisk.
At the southern end of the square are
two symmetrical churches on either side of the Via del
Corso, a street leading straight through the heart of
Rome to the
Piazza Venezia. The churches, the
Santa
Maria dei Miracoli and the
Santa Maria
in Montesanto 
were
commissioned by pope Alexander VII in 1658. They were
both designed by Carlo Rainaldi.
The churches are not
identical since the surface area for the Santa Maria
in Montesanto (on the left) was smaller. In order to
preserve symmetry, he created an oval dome for this
church and a circular dome for the Santa Maria dei Miracoli.