Route choice is typically assumed to be an optimisation process, where individuals minimise their distance or time costs while travelling between origin and destination. However, evidence from behavioural and neurological studies suggest that human navigation is considerably more complex process, influenced by cognition of space and variation in perception and preference. In this work, a large collection of minicab GPS route traces is examined in detail, with a range of approaches applied towards more comprehensively understanding route choice behaviour in urban areas. The analyses demonstrate the shortcomings of assumed optimisation on the part of the decision-maker, highlighting the role of heterogeneity in urban space and individual preference. In view of the findings, a behavioural framework is introduced as a possible way forward for the future modelling of route choice in urban areas.