Construction is underway on prototypes of Trump's border wall - see what they look like so far

Since last Tuesday, construction has been underway on eight prototypes for President Donald Trump's promised wall along the US-Mexico border.

US Customs and Border Protection selected six companies to construct the prototypes, which the agency said are meant to "inform future design standards" for the wall.

Although Trump's plans for a border wall have been beset by a number of obstacles - including the Senate's refusal to green light a $1.6 billion down payment, wavering estimates on the total cost, and a lawsuit from California - his administration has plowed ahead with the prototypes.

Here's what they look like so far: