* SPDR Gold TrustGLD , the world's largest gold-backedexchange-traded fund, said its holdings fell 1.5 percent onMonday. * U.S. retail sales unexpectedly fell in February, but arebound in factory activity in March and strong increase inconstruction spending offered hope the economy was not slowingas sharply as previously feared. * Euro zone headline and core inflation slowed in March,flash estimates showed on Monday, supporting the EuropeanCentral Bank's decision to delay a planned tightening ofmonetary policy.