Four days in La Serena: a city full of churches, and a valley with the clearest sky on earth

The centre is a small grid around the Plaza de Armas and the churches are the thing. La Serena has more of them per head than anywhere else in Chile, most founded in the first century after the conquest, burned or looted at some point by pirates or by earthquakes, and rebuilt in whatever style was current when the money appeared.

The cathedral on the main square is the oldest foundation, from 1544, with stained glass shipped from France. La Merced, a couple of streets away, goes back to 1558 and has a Gothic tower added in the nineteenth century that ought to look wrong and does not. San Agustin, a Jesuit foundation of 1672, has burned and been rebuilt more times than anyone bothers to count.

Between them, the small museum of religious art on the square holds vestments and silver from the eighteenth century, and it takes twenty minutes.

Book tomorrow's observatory session this evening, and check the moon.

The road east leaves the coast and within twenty minutes there is nothing green anywhere. Then the valley opens and there is a river, and vines on stone terraces climbing the sides of brown hills, and the contrast does not stop being strange for the whole hour.

The Puclaro dam sits partway up and is worth the ten minutes: a reservoir where a village used to be, with a permanent wind that has made it a windsurfing spot in the middle of a desert.

Vicuna is the main town, small and low, with a mock-Gothic wooden tower in the square that houses the tourist office. Gabriela Mistral was born here in 1889 and the museum is built around the adobe school house of her childhood. She won the Nobel Prize for Literature in 1945, the first Latin American writer to do so, and this is where to understand why the valley matters so much to Chileans.

Then the sky. Mamalluca sits on a hill above the town and runs sessions through the evening with a large telescope, a guide and a laser pointer, in Spanish and English. Two hours, booked in advance, and cancelled around the full moon.

Buses back to La Serena stop early, so either drive or arrange the observatory transfer, which most of them offer.

Today is the city's own, and it starts with the best thing in it. The archaeological museum holds more than twelve thousand objects covering the pre-Hispanic cultures of northern Chile, the Diaguita ceramics in particular, and it has a moai from Easter Island standing in the courtyard, which is startling to come across three and a half thousand kilometres from where it was carved.

The Gabriel Gonzalez Videla museum a few doors away is the counterweight: three and a half thousand pieces of local history and fine art, and the life of a president from this city whose record still divides Chileans.

In the afternoon walk or take a bus down the long avenue to the sea. The lighthouse at the end of it was built in 1950 and is the city's emblem, and the beach runs six kilometres from there towards Coquimbo. The water is cold and the sunsets are the point.

Eat somewhere along the front. This is the seafood coast and it is much cheaper than Santiago.

If you booked a professional observatory visit, this is the morning for it. Cerro Tololo, on a ridge about fifty kilometres inland, runs free Saturday tours by advance reservation and takes you among the domes of one of the most productive optical observatories in the world. La Silla, further out, does the same. Neither shows you stars; both show you the machinery, and the drive up is spectacular.

If you did not, spend the morning in the centre and go back to the valley for the papaya and the pisco you did not buy.

Buses south to Santiago take seven to eight hours and run through the day and night, and flights take an hour. North, the road runs to Antofagasta and eventually to Calama for the Atacama, which is a very long way by bus and much better flown.