As army after army, over large swathes of time, stormed across the Gangetic plains of India, they left their imprints on this chaotic collage of a great city called Delhi. The occupation of the British saw the final split in the personality of this ancient capital. Delhi reflects the schizophrenia of modern India perfectly. Split into New Delhi and Old Delhi, the capital manages to effectively sum up the passage of time, from an expectant techno-centric future to the chaotic present and into the archaeological realms of relics and ruins.
Modern Delhi is cut and paste of medieval fortifications, Mughal mausoleums, dusty bazaars, colonial-era town planning, and mega malls. You might tick off the sight-seeing list and be done with the city; eager to get away from the touts. Else, you might want to linger and take in the sunrise at Lodhi Gardens, check out the artistic quaintness of a modern day village at Hauz Khas or sway to the rhythm of Qawwali at Nizamuddin and fall in love.
Though the vastness of the city has become easily and comfortably traversable with the cheap and efficient metro, you might want to catch a much slower bicycle tour along the Yamuna or get familiar with the old city through the eyes of a former street kid.