The Baptistery of St John is a building of heterogeneous styles, due to the fact that the construction was carried out in several stages. The dome of the initial project has a truncated cone shape, and originally had a hole at the top to allow rainwater to enter and fill the basins. The absence of drainage channels, however, indicates that this was only decorative, as the old baptismal practice had long since been abandoned. In later times the second dome was built to close the forum. The absence of bricks throughout the dome has often been blamed on the lack of money available to complete the work. In fact, it seems that this was deliberate, as seaside towns used the reflection of the moon on the white bricks to help sailors find their way around.