Start by enjoying a sleep-in. Hell, you've been travelling for over four months now, why force yourself to be up and out of your hotel by 8am? Nothing's open before 9 or 10am anyway.
When you eventually head out, wander down past your local street stalls and pick up a fabulous purple handbag with all the pockets you like for 15 euros, and enjoy a piece of 2 euro pizza. Catch the Metro blue line to Colosseo, a great starting place for any walk around Old Rome. Bypass the strange men dressed as Gladiators (some with leopard-print cape, which you don't remember Russell Crowe ever wearing), and politely refuse all offers of "English tours through Colosseum, would you like to join our group?". Walk around the whole circumference of the "Flavian Amphitheatre", and congratulate yourself on knowing the original name of the structure. Take a photo in front of Constantine's Arch, stare up at the ruins of Palatine Hill, then make your way slowly but surely through to the Roman Forum.
Take your time wandering through this free open-air museum, with its dozens of columns, capitals, temples, fountains and drains. Imagine yourself in times past, strolling authoritatively down the Imperial Road in a purple toga, talking about that awful Caesar and how he double-crossed Xena, the Warrior Princess (remember, history is often better embellished).
Leave the forum and walk around the block to the Piazza Venezia and the imposing Monument to Victor Emmanuelle, first king of united Italy. Marvel at the 12m high and 10m wide bronze figure of old Vic on his horse, and at the sculpted figures of women underneath it, each representing an Italian city. Take your chances with the traffic and begin a stroll along the Via Del Corso, one of the city's most important streets - not least because it's stuffed with exclusive shops. Pretend you're Katie Holmes or Victoria Beckham and you're here to spend a lot of money. Better yet, don't.
After reaching the Piazza Popolo at the end of the Corso, track back through the side streets and chance upon the Spanish Steps. Feel slightly underwhelmed at the sight of some dirty white steps chockers full of hawkers and American college kids. By now it's late afternoon, a good time to wander past the famous Trevi Fountain. It may be a Monday afternoon in winter, but you will still have to fight your way down to the edge of the Rococo masterpiece to throw in the ubiquitous 1 cent coin, in order to ensure your return one day (hell, it worked last time).
Stroll through more side streets back to Piazza Barberini, picking yourself up a 4 euro wallet along the way. Take the crowded metro back home, enjoying the sensation of a strange man pressing up against your leg for three whole stops. Buy supplies at a local supermarket and cook yourself a big meal with carrots, broccoli and cauliflower, three vegetables you haven't had since October.
Get up slightly earlier, and make your way to the nearby Ostiense Station. Lose a 2 euro coin by sticking it in a broken ticket machine. Console yourself with a packet of Fonzies, the slighty-less-cheesy Italian version of Twisties. Eventually buy a ticket and take an overland train two stops to San Pietro, Vatican City. Follow the giant dome in front of you until you hit St Peter's Square. Go through the security checks and wind your way into the Basilica itself. Wonder as always at the massive interior, sumptous decoration and imposing dome. Venture underneath the floor to the Tombs of the Popes, now with John Paul II. Feel impressed by the fact he went for a simple white marble slab, rather than a lavish life-like scuplted image on top of a tomb decorated with Latin text praising his pontificate.
Leave the basilica, then the square, and walk about half a kilometre due east until you hit the Castel Sant'Angelo, which you haven't been inside before. Flash your MEAA Journalist card to gain free entrance, and marvel at a place that actually welcomes journalists! Regress back to your childhood as you twist and turn through the castle's many secret passageways and staircases, marvel at its impressive frescoes and take it its impressive views across all Rome from its many turrets and battlements.
Take a bus through the town to Termini Station, and walk a few blocks to the Church of Santa Maria Della Vittoria, which, you're kind of ashamed to admit, you only really learned about while reading Dan Brown's "Angels and Demons". Go inside and stare up at Bernini's sculpture, "The Ecstasy of St Teresa". Try not to get too embarrassed by the fact the St Teresa is obviously experiencing some sort of heavenly connection.
Wander back to the Metro station and jump on Line B once more, this time getting out at Circo Massimo. Walk along and down into the grassy remains of what was once ancient Rome's sporting arena. Past the Circus, and further on into a heavy traffic area, come across the iconic Bocca Della Verita, the "Mouth of Truth". The courtyard of the church in which the old sewer cover stands may be locked, but you can still take a photo through the gate.
Head back to the metro and head home for a final night in, full of vegetables and supermarket gelati. Congratulate yourself on spending less than 50 euros in two days in one of the most expensive of European cities. Figure that while Rome may be the Eternal City, you didn't do too badly with your two days' worth.