Ferroelectric domain reversal via electric field poling of congruently melting lithium niobate (LiNbO3) crystals is investigated. An electro-optic interferometric observation technique reveals spatial and temporal dynamics of the poling process. Starting from seeds, the domains grow until the entire crystal has a switched polarization. During the switching process the boundaries are preferentially aligned along the crystallographic axes. The coercive field between two sequenced domain inversions is transiently reduced after a poling event, and recovers exponentially with a time constant of about half a minute. No light-induced change of the recovery time constant, neither with green nor with ultraviolet light, is observed. The results are of relevance for domain engineering of LiNbO3 crystals.