Architecture
Much of Rome can be seen without spending a penny (unless you insist on casting your coppers into one of the city's many fountains). The glorious Pantheon, Hadrian's 2nd-century masterpiece, ought to be your first port of call, but arrive at 7pm and you can take advantage of a free 30-minute tour with the company Angel Tours.
Catch a glimpse of the nearby Piazza Navona, before braving the crowds at the Trevi Fountain. Then head for the Spanish Steps, an 18th-century addition to the city which is now surrounded by countless designer boutiques - each ideal for some forlorn window shopping.
Religion
Visitors are welcome to wander the ground floor of the cavernous St Peter's Basilica, while entrance to the Vatican Museum- which houses works by Titian, Poussin and several paintings by Caravaggio, as well as the Sistine Chapel - is free on the last Sunday of each month.
Sky Tours Rome offers free 30-minute tours of St Peter's Basilica at 9am every morning, except Sundays.
There are more than 900 other churches in Rome, many of which are free to explore.
Learning
A small number of museums and galleries are free to enter. The gallery at the National Academy of San Luca, which holds works by Rafael and van Dyck, the Historic Museum of the Liberation of Rome, on Via Tasso, and the Numismatic Museum of the Italian Mint, where visitors can peruse 20,000 medals and coins, are three of the best.
Unfortunately, the tradition of La Notte Bianca, a single night in September when all museums are free to enter throughout the night, has been abandoned since 2007, although the Italian Tourist Board says it may return in future.
Parks
Gianicolo Park, south of the Vatican, boasts wonderful views of Rome and plays host to a free puppet show each day.
Across town, the elegant gardens at the Villa Borghese are perfect for a romantic stroll. Entrance to the Galleria Borghese and the adjacent Villa Medici is not free.
Quirky Rome
Legend has it that if one tells a lie with one's hand inside La Bocca della Verita ("The Mouth of Truth"), it will be bitten clean off. Head to the church of Santa Maria in Cosmedin on the banks of the Tiber to put the myth to the test.
The Capuchin Crypt, meanwhile, is even more bizarre. Located beneath the Church of Santa Maria della Immacolata Concezione, it is a vast burial chamber decorated with the bones of some 4,000 Capuchin monks. With rooms such as the 'Crypt of the Skulls', the 'Crypt of the Pelvises' and the 'Crypt of Leg Bones', it's the perfect outing for bored teenagers. Entrance is free, although donations are encouraged