At the northern end of 5a Av is La Merced – a striking yellow building trimmed with white plaster filigree. Its facade is one of the most beautiful in Guatemala The squat, thick-walled structure was built to withstand earthquakes, and three centuries after its construction it remains in good shape. Only the church is still in use; a candlelit procession, accompanied by bell ringing and firecrackers, starts and ends here on the last Thursday evening of each month.
Inside the monastery ruins is a fountain 27m in diameter, said to be the largest in Hispanic America. It's in the shape of a water lily (traditionally a symbol of power for the Maya), and lily motifs also appear on the church's entrance arch. Go upstairs for a bird's-eye view of the fountain and the town.