Let me declare an interest immediately: I climbed Kilimanjaro as a middle-aged man doing something his knees had opinions about, and I wrote a whole book admitting it. So when someone in their fifties or sixties asks us, usually quietly, usually at the end of an email about something else, "honestly, am I too old for this?"

Over the past weeks we have compared Kilimanjaro, honestly, one mountain at a time, with the seven great treks and climbs it shares the world's daydreams with: Everest Base Camp, the Inca Trail, Mont Blanc, Elbrus, Aconcagua, Mount Kenya and its neighbour Meru. Every one of those pieces answered the same question: this one, or that one?

The final comparison in this series is the closest to our hearts, because these two mountains share a horizon. Mount Meru stands barely seventy kilometres from Kilimanjaro, close enough that from Meru's summit ridge at dawn you watch the sun rise directly behind the Roof of Africa, floating on the clouds across the plain.

Africa's two greatest mountains stand a border apart, and the comparison between them is the connoisseur's favourite, because it is the only one in this series where the quieter, lower, cheaper mountain has a genuine claim to being the more beautiful.