1969 was the first year in which genuine safety measures were implemented at circuits. The cars were going far faster over time, particularly with the increased engine capacity rules for 1966 onwards from 1.5 litres uncompressed to 3 litres uncompressed or 1.5 litres compressed, and the role that manipulated aerodynamics began to play in the cars' performance. The Montjuic circuit in Barcelona was a first in Grand Prix racing- the circuit was completely Armco-lined. Although safety measures in 1969 were still nearly non-existent compared to today's modern safety standards, these measures were a new step forward to protect drivers from further harm. About half the circuits in Formula One at this time had some safety standards, such as Silverstone, Magdalena Mixhuca in Mexico City and (less so) Monaco; although other circuits were nearly unchanged from previous years, such as the Nürburgring in Germany and the Clermont-Ferrand circuit in France; both were twisty mountain road circuits with all kinds of unprotected drop offs and solid obstacles on the sides of both circuits. Another example was the feared Spa-Francorchamps circuit in Belgium, an extremely fast public road circuit which was located in a similar area and had similar dangers to the Nürburgring and Clermont-Ferrand, such as unprotected drop offs and solid obstacles on the side of the track. The Belgian Grand Prix there was boycotted by many of the drivers because of the extreme danger of the track after an overall inspection of Spa by Jackie Stewart, who was responsible for most of the activities in Formula One to try to make it safer. He demanded changes to the circuit that the track owners did not want to pay for, so the race was boycotted and eventually cancelled. Spa was included in 1970 after Armco was added to some parts of the track.