Rome is huge, less so in space, and more so in meaning, richness, depth, the sheer number and the very attractiveness of its attractions.
I am devoting more detailed accounts to some of the must-see sites, buildings and museums, but decided to compile this little list in order to point out locations, objects and buildings that are not worthy of several hundred words each, but are still very much worth seeing and/or experiencing.
Thus this list of Lesser Sights but Still Icons, or Other Roman Things Very Much Worth Looking Out For.
1) Fontana di Trevi
Possibly the most famous of the Roman fountains, this exhuberant Baroque creation by Nicola Salvi was built in 1762 and remains one of Rome's iconic sights. Older visitors will fondly remember its appearance in La Dolce Vita, where it functioned as a fitting backdrop for the statuesque blonde Anita Ekberg. The fountain's sculpture depict Neptune's chariot led by Tritons with three horses and at night, the fountain is rather beautifully lit. People throw coins into the fountain to ensure their return to Rome (the second coin will mean you will fall in love with an Italian, the third that you will marry, so be careful). Over 100,000 Euro is retrieved annually from the fountain.
2) Bocca della Verita
A large stone disk in a shape of a bearded face mask, and of unknown origin (it is thought to be depicting some river god, possibly Oceanus), this is a Roman lie detector (its name means "the Mouth of Truth"), located in the portico of the church of Santa Maria in Cosmedin.
Starting from some time in the Middle Ages, it has been believed that if one told a lie with one's hand in the mouth of the mask, the mouth will snap shut. So far, everybody that submitted themselves to the Mouth's test has been proven truthful.
3) Piazza del Popolo
Overlooked in the shortest tours of Rome, this magnificent square to the north of the city centre is definitely worth a look and a stroll about. Designed in the 16th century, but re-modelled in the classicist style in the 19th, it's a monumental but beautiful space. The twin Baroque churches that flank the Piazza are almost - almost - identical.
4) Campo de' Fiori
Literally, the Field of Flowers, this is a lively piazza surrounded by a rather rambling architecture (it has never been formally designed) and traditionally a place of commercial activity and executions. It's perhaps most famous for the burning at the stake of Giordano Bruno in 1600, who held such dangerous ideas as heliocentrism and infinity of the universe.
Nowadays it's a busy market, but Bruno's statue still towers over the stall holders and nigh time revellers.
"On this same square
They burned Giordano Bruno.
Henchmen kindled the pyre
Close-pressed by the mob.
Before the flames had died
The taverns were full again,
Baskets of olives and lemons
Again on the vendors' shoulders."
[from the poem by Czeslaw Milosz]
5) Spanish Steps
Leading to Piazza di Spagna from the church of Trinita dei Monti, these magnificent steps built in 1725 have been traditionally a place of gathering for foreign visitors to Rome, and the locality has particularly strong associations with English Romantic poets: Keats died in a house nearby, now a museum devoted to him, Shelley and their fellow Romantics.
This famous if tiny building is universally recognised as the first Renaissance structure in Rome and one of the most perfect realisations of the Renaissance style in existence. Designed and built by Bramante around 1502, it was used numerous times as a model for later buildings.
7) Piazza Navona
Huge and beautiful piazza, lined with Baroque palaces, and a popular place for Romans and visitors, Piazza Navona is likely to be on your route even if you don't plan for it. It's worth paying attention to some magnificent fountains that grace the Piazza, including Fontana dei Quatro Fiumi by Bernini, Fontana del Moro and Fontana del Nettuno (19th century, but in keeping with the water theme of Bernini's masterpiece).
8) Via Giulia
A perfect Renaissance street, parallel to the Tiber designed by Bramante for Pope Julius II, lined with palazzos, shops and art galleries, and a wonderful place to just slowly walk by.
9) Ancient Via Appia and the catacombs
Including Via Appia on this list is perhaps risking something of an understatement, as The Appian Way was one of the earliest and most important Roman roads and connected Rome to Brindisi. Still falling somehow beyond the main scope of the central-Rome attractions, but easily accessible from beyond the Porta San Sebastiano, this ancient road is still a place worth visiting if you can make time for that. Along the road are situated several buildings of interest, including the church of Domine Quo Vadis as well as three catacombs of Roman and early Christian origin and the grand tomb of Caecilia Metella.
10) Monument to Vittorio Emanuelle II
This is one object after St Peter that you will be unlikely to miss. Designed by Giuseppe Sacconi in 1895, it was inaugurated in 1911 and completed in 1935 to commemorate the first king of unified Italy, and in his person, the act of unification itself. This huge, blazing white monstrosity of 19th century bombast has been unkindly called "the typewriter" or "the wedding cake" and yes, it somehow spoils the view of several more tasteful sites, but it's a Roman landmark nevertheless and the views are worth a climb.