The old town of Santiago de Compostela. [Provided To China Daily]

In 2015, 172,243 people walked or rode bikes or horses along the camino frances, according to the Pilgrims' Office in Santiago. More than 67,000 started in Sarria, about four days from Santiago, the end of the trail. The busiest months are May-September, with more than 20,000 pilgrims each, dropping to fewer than 900 in January. Over the last decade, yearly numbers have mostly risen, but 2010 saw the most pilgrims, likely because it was a Catholic "holy year".

I walked the entire camino twice, in May-June 2014 and September-October 2015, averaging 26 kilometers daily, often for hours without seeing another pilgrim - though I got stuck for a day among hundreds of yellow-hatted German confirmation students.

With the universal greeting of "buen camino", I met bikers from Taiwan, retirees from New Zealand, school groups from Minnesota and southern Spain, couples who started at 4 am to ensure solitude and singles who got a lively party scene going most nights. The only kind of person I did not meet was one not deeply affected by the experience.

Not everyone can devote four to five weeks to go the full way, however. Here are my favorite four-day stretches:

Roncesvalles to Estella

After the first pilgrims' blessing in half-a-dozen languages at the ancient stone church in Roncesvalles, a two-day downhill trek through mountain woods where Charlemagne fought and Hemingway fished takes you to Pamplona, one of four major cities the camino crosses. Refueled with Basque txistorra sausage, you're off through rolling hills carpeted in wheat and vines, topped by castles and crisscrossed by Roman roads and medieval bridges until Estella, whose fortress-like medieval churches and palaces huddle in a gorge.