The O2 Arena is a multi-event hosting arena, situated on Greenwich Peninsula in SE London. The name O2 comes from the primary sponsor, the O2 telecommunication services provider. The O2 Arena is the second ranked indoor arena in the United Kingdom, concerning its seating capacity. It replaced the Madison's Square Garden for being the busiest arena in the year 2008. It is also referred as the North Greenwich Arena. The arena has the largest building in the world regarding floor space. The seating arrangement of the dome-shaped arena is 20,000 that can be regulated as per the event. The main reason for which O2 arena was built was to reduce echoing and sound reverberations, a common problem in London. The O2 arena opens for only 200 days (roughly seven months) throughout the year.