A HUGE black box has mysteriously appeared in Southend High Street – and here is what it is for.

The box appeared in Southend City Centre this week and many have taken to social media to guess its use.  

Some suggestions have been a “huge knife amnesty bin”, others jokingly suggested the base of this year’s “Christmas tree” or a “new clock”.

However, the cube in question, pictured below, will form part of the Southend City Jam event.

Echo: Mystery - Black box in Southend High StreetMystery - Black box in Southend High Street (Image: Gaz De Vere)

Southend City Jam is a street-art festival that is being billed as the “largest in Europe”.

It will return on September 1 to September 3 with huge colourful piece of artwork scattered across the city.

The cube will be used as a collab for artists and will see each side of the huge cube painted by a different artist.

There will be a number of these placed across the city centre.

The event as a whole will see more than 200 artists - both national and local - provide colour to walls and cubes around Southend.

Some of these with be temporary but many will be permanent.