However tourists complained they did not see the “soaring views across central London and Hyde Park” from the lush landscape they were promised.
Instead they were treated to rubble, building sites and scaffolding from the 25m-high viewing platform after climbing up the brown turf-covered mound.
Westminster council, which commissioned the project, confirmed tickets were no longer on sale for this week and can only be booked from the beginning of August. Ticket holders can apply for a refund.
Sharing photos from visit, Emma Wright said: “Marble Arch Mound is the worst thing I’ve ever done in London.”
Dan Barker tweeted: “The original plan drawings and the marketing description do not quite match reality.
“In fact you can’t really see the park, as I presume it was designed in Winter, and Summer has filled the view with trees.
“To be fair, there is a narrow gap in the trees where you can see a bit of the park, but the foreground is somewhat less pretty. And looking east to the park, rather than south, you overlook an odd area full of rubble. I suppose that could be described as ‘striking views’.”
Others mocked the hill for its resemblance to the Teletubbies house and early video game scenery.
Westminster council apologised to the first visitors and said it was “resolving teething problems as they emerge”.
“We are aware that elements of the Marble Arch Mound are not yet ready for visitors,” a spokesman added. “We are working hard to resolve this over the next few days.
“In light of the delay, we are offering anybody who has booked a visit during the first week a return ticket free of charge so that they can enjoy the full experience and the landscape once it has had time to bed in and grow.
“People who visited the mound today, and people who are booked for the rest of the week, including the weekend, will be contacted and offered a refund and a free return ticket so they can see the mound at its best.”
The council had hoped the attraction would entice tourists back to central London after lockdown.
Up to 1000 visitors a day can climb the 130 steps to the viewing platform. On their way down they enter the hollowed out interior of the mound – designed by architects MVRDV – where there is a shop and cafe selling M&S food and drink.
The scaffolding “skeleton” is covered with sedum turf and trees, designed to create a green hillock in the heart of town.
Announcing its opening, Westminster council leader Rachael Robathan said: ”It is really important we do everything we can to encourage people to come back to the centre of our city and support businesses, the hospitality sector and our cultural institutions.”