We visited Las Medulas in May 2005, but used a car to drive up and around the site. If the weather is dry, a normal car would do, you don't need a 4WD. Using the car gave us a bit more time to look at the site from various different angles and to stroll around. It is absolutely stunning that this moon-like landscape has been created by humans with hardly any heavy tool available to them.
From the top you can also see quite a number of little lakes, which are the remains of redirected rivers used to wash out the gold deposits.