Using the surface brightness fluctuations in HST WFPC-2 images , we determine that M87 , NGC 4486B , and NGC 4478 are all at a distance of \sim 16 Mpc , while NGC 4476 lies in the background at \sim 21 Mpc .
We also examine the globular clusters of M87 using archived HST fields .
We detect the bimodal color distribution , and find that the amplitude of the red peak relative to the blue peak is greatest near the center .
This feature is in good agreement with the merger model of elliptical galaxy formation , where some of the clusters originated in progenitor galaxies while other formed during mergers .