It has been a long wait but 144 years after work began, Pope Leo XIV has blessed the recently completed central tower of Antoni Gaudí’s Sagrada Família church in the presence of members of the Spanish royal family, the prime minister and hundreds of bishops.

With the completion of the Jesus Christ tower, the tallest of 18 in the temple, the basilica has reached its full height of 172.5 metres. It is now not only the world’s tallest church but Barcelona’s tallest building. It was consecrated in 2010 by Pope Benedict XVI.

After a solemn Mass, the Pope, speaking in Spanish and Catalan, said that, more than a monument, “this basilica is a work in progress, which reminds us that the path that Christ has shown us is a journey that never ends”. He added: “We can never believe is a Jesus that wants us to make war or murder innocents.”

Before Wednesday’s service, Leo lit a candle and prayed at the tomb of Gaudí in the basilica’s crypt.

Ten hours before he was due to pass by, the faithful were already picking their spots along the pope’s route.

Ramón and Marisa from L’Hospitalet de Llobregat, both draped in Vatican flags, were among those who had arrived early to drink in the atmosphere. “We’re of the generation of John Paul II and Leo reminds us a lot of him,” Marisa said. “We’re very happy that he’s come here to Barcelona.”

Ramón said the Sagrada Família gives him goosebumps. “Gaudí deserves to be a saint just for building it,” Marisa said. “It’s a divine construction.”

A few blocks away, Rosmira Pasadis from Venezuela said she’d brought some fruit and water to get her through the long wait.

“This pope is very charismatic and he’s got a gift for communicating, especially with the young,” she said. “His visit is important for me not just because I’m a Catholic but because we hope he will call for the release of political prisoners in Venezuela and for our freedom.”

Security measures, which include the closure of several metro stations and streets, brought the city close to a standstill, while only invited guests can get anywhere near the Sagrada Família itself.

However, souvenir shops nearby were doing steady business selling pope memorabilia alongside their usual collection of Gaudiana tat.

Police estimated 70,000 people would line the route along the pope’s short journey, fewer than in Madrid and fewer still than the 650,000 who turned out for FC Barcelona’s players’ victory parade after they won the Spanish league in May.

Wednesday marks the centenary of the death of Gaudí, described by his biographer Gijs Van Hensbergen as “a man with a medieval soul and an avant-garde mind”.

Often known as God’s architect, Gaudí dedicated the last 12 years of his life to work on the Sagrada Família.

At a time when many in Barcelona were turning away from religion, Gaudí said he wanted to create a church for everyone, “a bible in stone”, hence the depiction of local people and scenes from everyday life among more conventional religious images.

According to the industrial historian James Douet, “the Sagrada Família was conceived to bring Barcelona’s disaffected industrial working classes back to Catholic beliefs, to turn them away from the anarchist violence and anti-clerical hostility that had become characteristic of the city, and in some way to expiate or atone for the sinfulness of its inhabitants”.

Blessing the towers was the last stop in Leo’s busy Barcelona schedule that has included an audience with the Catalan president Salvador Illa, a visit to a high-security prison, saying the rosary at the monastery at Montserrat and a plea for Catalan unity delivered in Spanish and Catalan.

Although the Sagrada Família has reached its full height, completion of the Glory facade of the main entrance is still a decade away, and then there’s the construction of the contentious grand stairway – which would entail rehousing between 1,000 and 10,000 people, depending on which plan is implemented.

The dispute over whether what we see today has anything to do with what Gaudí intended is bound to rumble on. As long ago as 1965 a group of artists and architects, among them Le Corbusier, Ricardo Bofill and Joan Miró, said work on the basilica should stop, citing “the mediocrity of the promoters who are using Gaudí to make their mark to the detriment of the original work”.

However, Jordi Faulí, the architect charged with completing the work, says Gaudí understood that only a small part of the temple would be built in his lifetime and left detailed drawings and instructions that – although several were subsequently lost or destroyed – are enough to ensure that his successors can realise his vision.

The question of Gaudí’s beatification remains. Last year Pope Francis authorised a decree declaring the architect “venerable”, an early step on the road to being canonised by the Catholic church.

The Sagrada Família is visited by about 5 million people a year, each paying upwards of €26 (£22), making it good business for the Catholic church. If Gaudí is beatified it could become a place of pilgrimage as well as a tourist destination.

However, Mateu Hernández, the head of Visit Barcelona, emphasised the city’s secular status when he said it now had “a global icon equal to the Eiffel Tower, the Taj Mahal or the Pyramids”.

In the century and a half since work began on the temple, Barcelona has continued to be a city more inclined to rebellion than prayer. Time will tell whether Pope Leo’s visit will lead its rebellious citizens back towards the path of righteousness.