A vast white marble monument to Victor Emmanuel II, the first king of a unified Italy, built at the turn of the twentieth century and finished after decades of work.

It is the most divisive building in the city. Romans have called it the wedding cake, the typewriter and the false teeth, and the criticism is not only aesthetic — a medieval quarter was demolished to make room for it, and its scale and blinding white marble sit awkwardly against the brick and travertine of everything around.

Visitors are generally kinder than locals, and a great many describe it as one of the most impressive things they saw.

Whatever you think of it from below, the reason to go is what is on top.

It is also known as the Altare della Patria, the Altar of the Fatherland, and both names refer to the same building.

An important distinction that catches people out.

The main staircases, the terraces partway up and the Tomb of the Unknown Soldier are free. You can walk up a substantial part of the monument, get a good view over Piazza Venezia and along Via dei Fori Imperiali toward the Colosseum, and pay nothing.

What is ticketed is the panoramic roof terrace at the very top, reached by a glass lift from the upper level.

The terrace ticket is modest and generally includes the museums inside the building — the Risorgimento museum, a flag museum and whatever temporary exhibition is running.

So the decision is not whether to visit but whether to pay for the last thirty metres. Almost everyone who does says it was worth it.

The reason to buy the ticket, and the strongest single view in Rome.

The terrace runs along the top of the monument and gives a full three-hundred-and-sixty degree panorama: the Roman Forum and the Colosseum on one side, the domes of the historic centre and St Peter’s on another, the Capitoline and the Palatine below, and the hills beyond.

What makes it unique is that you are in the middle of the city rather than on its edge. The Janiculum and Piazzale Michelangelo equivalents look at Rome from outside; this looks at it from the centre outward.

Access is by a glass lift from the upper terrace, which is itself part of the experience.

The queue for the lift is usually short. Ticket machines at the entrance to the terrace section are quick and often have almost no queue even at midday.

At the centre of the monument’s lower terrace, beneath the equestrian statue, lies the tomb of an unidentified Italian soldier of the First World War, with an eternal flame and a permanent honour guard.

It is a working national memorial rather than a display. Soldiers stand watch and there is a changing of the guard through the day.

Behaviour is expected to reflect that: no sitting on the steps around it, no eating, and staff will move you on. Rome’s police have historically been strict about people treating the monument’s steps as a picnic spot.

For Italians this is the equivalent of a national cenotaph, and the contrast between the tourist crowd on the steps and the ceremonial guard a few metres away is part of the experience.

It is free and takes five minutes.

Generally included with the terrace ticket and comprehensively ignored by most visitors.

The Central Museum of the Risorgimento covers the unification of Italy in the nineteenth century — genuinely interesting if that period appeals and skippable if it does not.

A flag museum holds military standards.

Temporary exhibitions occupy a large gallery space and are often substantial, sometimes major touring shows.

Because they come with the terrace ticket, they cost nothing extra. Several visitors describe the museums as the surprise of the visit and are glad they wandered in.

Check what exhibition is running before you go — occasionally it is the reason to buy the ticket rather than an afterthought.

Fifteen to twenty minutes for the free terraces and the Tomb of the Unknown Soldier.

Forty-five minutes to an hour including the lift, the roof terrace and time at the rail.

Two hours if you are taking in the museums and an exhibition properly.

It sits directly between the historic centre and the Forum, so it is a natural stop rather than a destination — most people arrive on the way from one to the other.

One planning note: the museums and the terrace close earlier than the outdoor areas, and visitors arriving late in the day find they can climb the steps but not get to the top.

Late afternoon is the best for the terrace. The light on the Forum and the Colosseum from up there in the last hours is the version worth having, and the marble is less blinding than at midday.

Early is quietest.

Midday in summer is punishing — this is white marble in full sun with no shade anywhere on the monument, and the glare is genuinely uncomfortable.

After dark the exterior is floodlit and Piazza Venezia below is one of the more dramatic night scenes in Rome, though the terrace will have closed.

Check the closing times for the terrace and museums, which are earlier than you might assume and vary by season.

The visit pattern here is unusually flat across the year, which reflects how many people stop off in passing rather than making a special trip.

April, May, June and March are the busiest, with January the quietest.

Unlike most Rome sites, the summer months are not the peak — the exposed white marble in July and August is exactly as unpleasant as it sounds, and visitors avoid it.

Spring and autumn are the best combination of light, temperature and clarity.

Winter gives the sharpest long views from the terrace on a cold clear day, with almost nobody else up there.

The monument stands on Piazza Venezia, the traffic hub at the exact centre of Rome, where several major roads meet.

Everything converges here. From the Colosseum it is a ten-minute walk up Via dei Fori Imperiali. From the Pantheon or Piazza Navona, ten to fifteen minutes. From Termini, about twenty.

Buses stop all around the piazza and it is the single best-connected surface transport point in the city.

The nearest metro is Colosseo, a walk away.

Crossing Piazza Venezia on foot requires attention — the traffic circulates constantly and the crossings are not always obvious. Use the marked crossings rather than improvising.

The monument’s position makes it the hinge of central Rome.

Behind it, steps lead up to the Capitoline Hill, Michelangelo’s square, and the Capitoline Museums — which hold the she-wolf, the Marcus Aurelius bronze and a terrace looking down over the Forum that is free to reach.

The Roman Forum and the Colosseum are along Via dei Fori Imperiali, ten minutes away.

The Pantheon, Piazza Navona and Trevi are all within fifteen minutes on foot.

The church of Santa Maria in Aracoeli, up a long flight of steps beside the monument, is free and worth the climb.

If you are working out a walking route through Rome, this building is where the halves of the city meet.

Better than the exterior suggests. The monument is famously a mountain of steps, but there are lifts.

The glass lift serves the roof terrace from the upper level, and there is lift access within the building to the museum floors.

Getting from street level to the point where the lifts start does involve steps on the main frontage, so check the accessible entrance arrangements in advance — access is possible but not from the obvious staircase.

Accessible toilets are available inside.

The terrace itself is level once you are on it, with a rail all the way round.

For anyone who cannot climb at all, the Capitoline terrace behind the monument gives a free level view over the Forum.

There is a café on the route to the terrace, positioned well past the halfway point, with a view.

Toilets are available inside the ticketed section.

The steps outside are patrolled and sitting, eating or lounging on them will get you moved on — this is a war memorial, and it is treated as one.

There is no shade anywhere on the monument, so a hat and water are worth having in summer.

Street sellers and the usual approaches operate around Piazza Venezia, and the crossings are busy, so keep bags in front.

The reviews are far warmer than the building’s reputation would suggest, and the criticism is almost all aesthetic rather than practical.

The minimal version: look up at it from Piazza Venezia, agree it looks like a wedding cake, photograph it, and walk on to the Forum.

The good version: climb the free steps, pause at the Tomb of the Unknown Soldier, buy the modest terrace ticket, wander the museums that come with it, take the glass lift to the roof in the late afternoon, and stand at the rail looking at the Forum, the Colosseum and every dome in Rome at once.

Romans may dislike the building. Nobody dislikes the view from the top of it, and it is the cheapest great thing in the city.