Barcelona's two terminals sit four kilometres apart and the train only serves one of them, which is why the best route in is different depending on where you land. What each option costs in time, the ticket that works on the train but not the metro, and the metro that does not reach the centre.
Rome's tap water is among the best of any major European city, and the cast iron nasoni running on street corners are fed by the same supply. Which fountains are for drinking, which are decorative, and the small trick Romans use that most visitors never notice.
Barcelona's tap water is treated to European standards and safe to drink, but a lot of locals buy bottled anyway, which visitors reasonably read as a warning. Why the water tastes the way it does, how to ask for it in restaurants, and what the habit actually costs you.
Most of what makes Rome extraordinary is outdoors and unticketed, which means three days here can cost nothing in admission. Churches that function as free museums, the views that need no booking, where the drinking water is, and what the free museum Sundays really cost you.
Rome needs more time than its size suggests, because the Colosseum and the Vatican are half day commitments rather than stops on a walking route. What each day actually buys you, the timed ticket problem that catches first visitors, and how the season changes the answer.
Copenhagen is compact, flat and organised, which makes a short visit efficient rather than rushed. What three days cover, why cost usually decides the length of the trip rather than the sights, how to eat well for a fraction of restaurant prices, and when the season matters more than the itinerary.
Athens is smaller on foot than its sprawl suggests, and the ancient sites cluster tightly enough that two days genuinely covers them. How the heat changes the answer, why the first Acropolis slot matters more than anywhere else in Europe, and when a third day is worth it.
London is roughly ten times the area of Paris within its inner ring, which makes travel time the constraint rather than the number of attractions. How to divide four days by geography, why free national museums change the arithmetic, and the authorisation you now need before you fly.
Venice is small enough to walk end to end in an hour, which misleads people into booking a day trip. Why two nights beats one long day, how the access fee changes the arithmetic on around 60 peak dates in 2026, and the registration step that catches even exempt visitors.
No rule stops you checking a laptop, yet the FAA advises against it and airlines limit liability for electronics in the hold. A look at the lithium battery rules, why cargo compartments are the concern, what happens when a cabin bag is gate checked, and when checking a machine is defensible.
