The Arch - Kensington Gardens, London, UK - Satellite Imagery Oddities on Waymarking.com

The Royal Parks website advises:

"The Arch is a six-metre high Roman travertine sculpture positioned on the north bank of the Long Water. It was presented by the artist Henry Moore to the nation for siting in Kensington Gardens in 1980 - two years after his eightieth-birthday exhibition at the Serpentine Gallery, London.

The Arch is made from seven travertine stones weighing a total of 37 tonnes. The stones were sourced from a quarry in northern Italy.

After being disassembled in 1996 due to structural instability, The Arch has been recently restored at its original location in Kensington Gardens by The Royal Parks and The Henry Moore Foundation."

Wikipedia has an article about The Arch that tells us:

"The Arch 1979–1980 is a large stone sculpture by Henry Moore located in Kensington Gardens in Hyde Park, London. It was given to the park by Moore in 1980. The Arch was found to be unstable in 1996, and was subsequently dismantled and placed into storage. It was restored and replaced in its original location in 2012.

"After the 1978 exhibition at the Serpentine Gallery in London, in which several large pieces were located in Kensington Gardens, there was a request for me to leave a sculpture there permanently, which I agreed to do. I thought the Large Arch was very naturally sited, particularly as it could be seen reflected in the water from across the lake. During the exhibition, many people believed the sculpture to be made of marble, but in fact it was a fibreglass exhibition cast made originally for my exhibition at the Forte di Belvedere in Florence (1963), because of the difficulty of getting a very heavy bronze or marble on to the site. Therefore, so that it could be left as a permanent sculpture in Kensington Gardens, I produced a version in travertine marble which is a very lasting material.""