the distance is known), from detached binaries, from the termination of the white-dwarf sequence, and from the luminosity function method which provides a joint constraint on the age and distance of a GC. @R+96 determine the distance to NGC 6752 by means of accurate photometry of GC white dwarfs and obtained an age of $14.5 \pm 1.5$ Gyr. Using the same method they find 47 Tucanae to have an age of $13
\pm 2.5$ Gyr [@Zoccali+01]. @Gratton+97, using the new [*Hipparcos*]{} distance scale to determine main-sequence turn-offs, estimate an age of $11.8^{+2.1}_{-2.5}$ Gyr (95% confidence level) for the oldest Galactic GCs. [@JimenezPadoan97] apply the luminosity function method to M55 and obtain an age of $12.5 \pm 1.0$ Gyr (95% confidence level). @Hansen+02, using very deep [*HST*]{} images, find the white dwarf cooling sequence for M4 and estimate its age to be $12.7 \pm 0.7$ Gyr at the $95$% confidence level. Using the theoretical age–mass relation and applying it to the detached eclipsing binary OGLEGC-17, [@ChaboyerKrauss02] determine Omega Centauri to have an age of $11.2 \pm 1.1$ Gyr (95% confidence level). These age estimates are all remarkably consistent. @KraussChaboyer03 perform the most careful analysis to date of the effects of systematics 