Hermann Tilke has hit back at claims that he is the architect of today's 'boring' Formula 1 circuits.
The German and his company have been in charge of the design of newer circuits throughout the F1 calendar, including China, Sochi, Bahrain and Abu Dhabi.
"We never had a clean sheet of paper to start with," Tilke told Italy's La Repubblica.
"There are many limitations, one of them being the safety regulations that have evolved since the death of Ayrton Senna and are still evolving.
"But it's always a piece of land that we do not own, so we need to respect cultural and historical traditions. Then there are the costs, with investors wanting multi-purpose facilities.
"The latest project is in Hanoi and we hope to be ready for next year," he added. "The time available is not much but we are used to that."
Tilke said drivers often help him with the actual design of the circuit layout, but none more so than Michael Schumacher.
"I owe a lot to him," he said.
"I showed him my first sketches and he always gave me a lot of his time providing useful suggestions to improve them.
"Even today some drivers help me, but none of them like Michael did."
