Almost 50 million euros: mind-blowing details of the billionaire's wedding have emerged

The world's rich and famous have descended on Venice for a three-day wedding party hosted by Amazon billionaire Jeff Bezos and his wife-to-be Lauren Sanchez, amid protests in the city of lagoons.

US reality TV hosts Kim and Khloe Kardashian were spotted climbing into water taxis in stilettos, while Kris Jenner, Oprah Winfrey, Leonardo DiCaprio, Orlando Bloom and Queen Rania of Jordan were also among the guests at the mega-wedding.

According to The Guardian, Donald Trump's daughter Ivanka was one of the first of about 200 guests to arrive and, despite the stifling heat, spent her pre-wedding time sightseeing and shopping.

More than 90 private jets flew guests to Marco Polo Airport for what was dubbed the "wedding of the century", while others arrived in Venice on their superyachts.

Jeff Bezos, the world's fourth-richest man, and Lauren Sanchez, a former television journalist, kicked off the celebrations with a party Thursday night at the Madonna dell'Orto monastery, a 14th-century church in the Cannaregio neighborhood that houses masterpieces by Italian Renaissance artist Tintoretto.

By early evening, the bridge leading to the church's front was blocked off by private security guards, while police stood by. Music blared and a small corridor of black screens kept guests anonymous as they exited the water taxis. Among them was DiCaprio, wearing a dark baseball cap pulled low over his eyes, The Guardian reports.

Venice authorities stepped up security measures across the city, banning pedestrians and boats from the area where the festivities were taking place on Thursday evening from 4:30 p.m. local time until midnight in an attempt to thwart protesters who had threatened to disrupt the party.

The wedding is said to cost between 40 and 48 million euros.

The bride and groom arrived in Venice by helicopter on Wednesday and checked into the seven-star Aman hotel, where George and Amal Clooney stayed during their wedding in 2014. Rooms overlooking the Grand Canal cost at least 4,000 euros a night.

The couple were spotted leaving the hotel around dinner time, with Sanchez wearing a vintage Alexander McQueen dress - one of 27 outfits reportedly made especially for the occasion.

Kagdas Halicilar, a German professional who looks like Jeff Bezos, tried his best to confuse the crowd by posing for photos outside the Aman Hotel before heading to the party venue.

On Thursday afternoon, celebrities were seen leaving the Gritti Palace Hotel dressed up for the first event of the evening. Kim Kardashian opted for a form-fitting snakeskin dress, while Ivanka Trump was pictured in a cherry blossom-patterned Oscar de la Renta cocktail dress. Also spotted that day were Usher in a cream suit and burgundy low-cut shirt, and Leonardo DiCaprio, who covered his face with a black cap.

Protests have raged for weeks ahead of the wedding, which critics say threatens to turn the UNESCO World Heritage site, already visited by millions of tourists each year, into a playground for the rich.

Luca Zaia, president of the Veneto region, said the couple had increased their donation to a project to study the city's lagoon system from €1 million to €2 million.

Bezos and Sanchez will reportedly exchange vows on Friday in a ceremony on the tiny island of San Giorgio Maggiore, where they will be serenaded by Matteo Bocelli, the son of famed opera singer Andrea Bocelli. The island is home to a basilica filled with masterpieces including Tintoretto's Last Supper, an amphitheater and a kilometer-long labyrinth.

The main wedding reception is expected to take place on Saturday at the Arsenal, a historic shipyard complex surrounded by fortified walls. A big party was due to take place in a 16th-century building in the city centre but was postponed due to security concerns.

The celebrations are said to include a pajama party, a foam party and a Great Gatsby-themed event in the coming days.

It remains unclear when the couple will officially tie the knot (they are thought to have already tied the knot in the US before this week). A Venice City Hall spokesperson told CNN on Thursday that the city had not received a formal request from the couple, meaning this week's events will be ceremonial and not legally binding.

The wedding's complex planning is being handled by Lanza and Bausina - the planners who also oversaw Clooney's star-studded Venice nuptials - who told CNN that their clients' instructions were to minimize "any disruption to the city," while insisting that they were using an overwhelming number of local vendors to stage the event.

The couple sources about 80% of their wedding supplies from local vendors, including baked goods from Venice's oldest pastry shop, Rosa Salva, and gifts from Murano glassware designer Laguna B.

A total of about 30 of the city's 280 luxury water taxis are also believed to be reserved. One taxi driver told CNN he had a reservation for June 25-30 for a "big wedding," but declined to provide details. Gondola service has also been suspended, and the city's gondola association confirmed they are ready for the event.