  We measure and analyse the sizes of 82 massive (M >= 10^11 M_Sun) galaxies at
1.7<z<3 utilizing deep HST NICMOS data taken in the GOODS North and South
fields. Our sample provides the first statistical study of massive galaxy sizes
at z>2. We split our sample into disk-like (Sersic index n<=2) and
spheroid-like (Sersic index n>2) galaxies, and find that at a given stellar
mass, disk-like galaxies at z~2.3 are a factor of 2.6+/-0.3 smaller than
present day equal mass systems, and spheroid-like galaxies at the same redshift
are 4.3+/-0.7 times smaller than comparatively massive elliptical galaxies
today. We furthermore show that the stellar mass densities of very massive
galaxies at z~2.5 are similar to present-day globular clusters with values
~2x10^10 M_Sun kpc^-3
