Several of the front pages show Julian Cadman - the seven year old who died in the Barcelona attack.
"Our Beloved Cheeky Julian" is the headline for the Mirror, quoting his family's tribute to their "much loved and adored" boy.
The Times describes a "solemn" ceremony at the La Sagrada Familia cathedral attended by Spain's King Felipe and Queen Letizia.
It says the unfinished basilica was a likely target of the attackers, had their suspected bomb factory not exploded.
The Times leads on figures showing what it calls an "unprecedented spending spree" by gambling firms on advertising.
They spent £312m on adverts last year, according to the research company Nielsen - a rise of nearly two thirds compared with five years ago.
Experts worry that children are particularly at risk, due to exposure to special offers on social media, and pre-watershed adverts during televised football matches.
The report carries a call from a leading addiction charity, urging ministers to tighten the rules governing when and how betting is advertised.
The government's chief trade negotiation adviser, writing in the Daily Telegraph, predicts Britain's post-Brexit trade agreements will make the world a safer place.
Crawford Falconer, who starts work at the Department for International Trade this week, believes the UK can promote stability by striking deals with countries who want to benefit from its democratic reputation.
He warns that history is littered with the destructive consequences of closed markets.
The Daily Mail returns to the topic of highly-paid BBC presenters.
A Freedom of Information request submitted by the paper reveals that 66 of the corporation's biggest earners have their salaries routed through so-called "personal service" firms.
The Mail claims it is so they can avoid paying income tax - a practice, it says, BBC bosses pledged to stamp out five years ago.
A BBC spokesman said all its contracts require people to pay the correct level of tax.
The Sun blames House of Commons bureaucrats for Big Ben's impending four-year silence.
It says officials admitted they didn't flag up the changes because they didn't think anyone would care.
In an editorial, the paper asks if the notion of common sense "rings any bells".
The Telegraph is similarly vexed, pointing the finger at the Commons speaker John Bercow as the man responsible for insisting the plan goes ahead, in spite of resistance.
The Daily Mirror reveals details of a shortfall in new joiners to the British Army.
The paper reports that the common infantry course at Catterick - the army's biggest base - saw only 14 of its 96 places filled this year.
It's symptomatic of a recruitment crisis gripping the military, the Mirror argues, citing further data that shows a third of places at courses across the country since June 2015 were left vacant.
In an editorial, the paper blames the privatisation of army recruitment and accuses the Conservatives of presiding over a "national scandal".
The Prince of Wales' popularity has slumped, according to a YouGov poll featured on the front page of the Daily Mail.
Only a third of the 1,500 questioned believe Prince Charles has been beneficial for the Royal Family - down from nearly two thirds in 2013.
The royal commentator Penny Junor tells the paper the public have never forgiven the prince for the collapse of his relationship with Diana.
Meanwhile, the Sun has spoken to Diana's former private secretary, Michael Gibbins, who claims that the princess' relationship with Dodi Al-Fayed was a fling that wouldn't have lasted beyond the summer.
And finally, several papers look back on the life of the veteran Hollywood comic Jerry Lewis.
The Daily Mirror recalls how, as a young man, the Rat Pack star would live as his character both on stage and off it - sneaking into local kitchens to steal pies and fried chicken.
The Express highlights his popularity outside the US. In France, for example, his slapstick style led him to be revered as an absurdist auteur.