In the tomb of Ti, an inclined passage, starting from the middle of the first hall, leads from the upper world to the sepulchral vault; but this is almost a solitary exception.

Generally, the vault is reached by way of a vertical shaft constructed in the centre of the platform (fig.

133), or, more rarely, in a corner of the chapel.

The depth of this shaft varies from 10 to 100 feet.

It is carried down through the masonry: it pierces the rock; and at the bottom, a low passage, in which it is not possible to walk upright, leads in a southward direction to the vault.