We are performing a thorough analysis of the internal colour gradients
of early-type galaxies (ETGs), examining a sample of about 5,000
nearby massive systems, with optical+NIR data from SDSS+UKIDSS-LAS
surveys. The large wavelength baseline (including grizYJHK wavebands)
helps us to infer age and metallicity radial gradients of ETGs,
minimizing the effect of the age-metallicity "conspiracy".  I will
discuss how colour, age, and metallicity gradients depend on
galaxy properties (e.g. mass), as well as on the environment where
ETGs reside (i.e. field, groups, and clusters). These dependencies
imply new constrains on our picture of how the most massive galaxies
form and evolve.