if it was around 7 in the evening a shot which reflects the mood and ambience might be more appropriate. adjusting levels or brightness in photoshop is acceptable up to a certain level; past that & the loss of details will make the shot look too artificial. as it is, your shot suggests that it was taken when the sun was either setting or in high afternoon.
again, i feel that where flags are concerned, colours are really really important, especially so because each colour represents something. taking that away gives the flag a rather sterile feel to it.
but that's just my opinion.