Olympia - Hammersmith Road, London, UK - Satellite Imagery Oddities on Waymarking.com

Olympia is an exhibition and conference centre in west London. There are four event halls ranging in size from 7,700 sq m to 19,300sq m and a conference hall. Olympia has its own railway station, Kensington (Olympia), that is served by both London Underground and London Overground. The building was originally created in 1884 as the National Agricultural Hall and soon changed its name to Olympia.

Wikipedia has an article about Olympia that tells us:

Olympia is an exhibition centre, event space and conference centre in West Kensington, London, England.

Opened in 1886 as the National Agricultural Hall, it was built by Andrew Handyside and Company of Derby and covered an area of 4 acres (16,000 m2). The Grand Hall, 450 feet (140 m) in length, by 250 feet (76 m) in breadth, was said to be the largest building in the United Kingdom covered by one span of iron and glass.

It now features four event venues and a conference centre. The event venues are Olympia Grand (19,325m²), Olympia National (8,730m²), Olympia Central (formerly Two) (7,850m²) and Olympia West (7,688m²).

The nearest railway station is Kensington (Olympia) which is both a London Overground station and on the District line of the London Underground.