The nice thing about cruising on the Mediterranean is when someone sends you a text message asking: "what are you doing tomorrow?" You can say: "I'm going to Rome for the day."
We said goodbye to our Viking Cruises Mediterranean Odyssey trip in the Eternal City, but it carries on through Greece and Croatia before finishing in Venice.
Our ship, the Viking Star, offers many tour options in Rome but as we were leaving that day we opted for a hop-on, hop-off bus ride, which takes you around the city and is a great way to see the main sights and get your bearings from the open-top deck while avoiding the crowds below.
There aren't enough adjectives for Rome. It looks like a massive archaeological site.
Jaw-dropping sights are everywhere and if you take the time to go to the Vatican you can see Michelangelo's Pieta or the Sistine Chapel, but even if you don't get off the bus you still get your fill of the immensity of what is on offer.
Over there, for example, is where they used to have chariot races (and where Ben-Hur was filmed) Julius Caesar was assassinated over there at the Theatre of Pompey, and over there, overlooking the Piazza Venezia, is Mussolini's balcony where the fascist World War II leader roused the crowds.
Rome boasts 100 monumental fountains and 2000 drinking fountains, a tonne of thermal baths, where past inhabitants liked to spend a leisurely day, and 44 centuries of continuous urban life.
Talk on board the ship the night before was about the infamous Medici family, wealthy patrons of the arts - Raphael, Michelangelo and Donatello painted for their coin. Some form the powerful clan became popes, other merely princes.
We stopped at Pisa the day before Rome, from where many passengers went to Florence for the day but I opted for the Pisa tour.
It's a bit of a fight to get to the Leaning Tower - we got stern warnings from our guide to beware of the pickpockets among crowded tourist stalls and many hawkers of "genuine" Rolexes and Prada bags.
But around the corner there is the tower, leaning and gleaming in the sun in the piazza they call Miracle Square, which also has a church, baptistery and cemetery.
The tower began to lean soon after construction began, guide Julia says, because the soil is poor. It's soft and is made of water, sand and clay.
At 60 metres high and with 15,000 tonnes of construction material, it's heavy (there are 293 stairs, all made of marble). Construction was halted for an entire century after the tower began to sink but it was finished at the end of the 1300s.
Julia says because it's the bell tower for the cathedral, the tower is an important part of the church and construction couldn't be easily restarted. After the first three floors, building began in the opposite direction to try to correct the lean and balance the tower but it didn't straighten up.
In the 1990s, 1000 tonnes of lead were put in to try to balance it again and, at the last check, in 2011, it hadn't moved a single millimetre.
Astronomer and physicist Galileo Galilei was born in Pisa.
He developed the law of the isochronism of pendulums while watching a lamp swinging at the cathedral, and discovered, Julia says, "that the time of the oscillation of a pendulum doesn't depend on the angle of oscillation but it depends on the length of the pendulum itself".
Over in the baptistery they used to have full immersion baptisms.
Now they just sprinkle the person being baptised with water - but it's interesting to think of Galileo being fully immersed here in the 15th century.
The baptistery is also famous for its acoustics. On our visit, a man demonstrated this phenomenon; the acoustics made his voice sound as if a choir was singing.
Back outside Julia reveals the tower is not the only leaning tower in Pisa, but she says it's the most beautiful one.
Most of the buildings in town lean, she says, and she directs the way to another leaning bell tower, at the San Nicola Church a short walk away, though the lean there isn't as severe. Most people live in leaning homes, she says, but they only lean a few degrees so "no, you don't fall out of bed".
Viking's seven-night 'Iconic Western Mediterranean' cruise is on sale through helloworld, with fares starting from $6099pp. It includes one shore excursion in each port.