No matter how many pictures you’ve seen, the first impression you’ll have of the Colosseum is amazement at its sheer enormity. It is massive and looks as if it has been plopped down among the surrounding buildings, and not the other way around.

Your first view of the Flavian Amphitheater (the Colosseum’s original name) should be from the outside, and it’s important to walk completely around its 500m (1,640-ft.) circumference. It doesn’t matter where you start, but do the circle and look at the various stages of ruin before delving in. Note the different column styles on each level. A conservation makeover will run throughout 2016, to consolidate the structure and remove soot and pollution marks.

Once inside, walk onto the partially reconstructed wooden platform flooring that once covered the hypogeum, the place that is, where gladiators and beasts waited their turn in the arena. Vespasian ordered the construction of the elliptical bowl, called the Amphitheatrum Flavium, in A.D. 72; it was inaugurated by Titus in A.D. 80 with a bloody combat, lasting many weeks, between gladiators and wild beasts. The stadium could hold as many as 87,000 spectators by some counts, and seats were sectioned on three levels, dividing the people by social rank and gender. There were 80 entrances and historians say the massive crowds could be seated within a few minutes. Most events were free, but all spectators had to obtain a terra-cotta disc, called a tessera, to enter.

The Colosseum was built as a venue for gladiator contests and wild animal fights, but when the Roman Empire fell, it was abandoned and eventually overgrown with vegetation. You’ll notice on the top of the “good side,” as locals call it, that there are a few remaining supports that once held the canvas awning that covered the stadium during rain or for the summer heat. Much of the ancient travertine that covered its outside was used for palaces like the nearby Palazzo Venezia and Palazzo Cancelleria near the Campo de’ Fiori.

An ongoing conservation effort, funded by the Italian design house Tod's, helped eliminate nearly 2,000 years of soot from the monument's exterior; restoration efforts have now shifted to its underground vaults and passageways. Access to the Colosseum Underground and Belvedere (upper tier) is by guided tour only, ticketed separately from admission to the Colosseum (and not included with the RomaPass). The process for purchasing tickets online can be baffling, but essentially you can reserve a tour of the underground OR the belvedere OR both areas, up to one month in advance. These tours sell out very quickly. A combined tour costs 15€, in addition to the 12€ admission fee. Remember that the same ticket you buy for the Colosseum includes admission to the Forum and Palatine Hill, and is valid for 2 days.

Note that as of spring, 2019, all visitors to the Colosseum must purchase a timed entry ticket. Though a limited amount of same-day tickets may be available for walk-up visitors, we wouldn’t risk it. Buy your ticket well in advance through the official website, and print or download it before your visit. You still must go through security screening, which can take up to an hour on busy days. RomaPass holders must also reserve a time to enter the Colosseum, either online or by calling tel. 06-39967575. There’s a 2€ per person service charge to reserve a time.