The  term 'mausoleum', with which we mean a monumental tomb, comes from Mausolus' tomb, king of Caria, in Alicarnassus (moderm Bodrum, south western Turkey). The beauty of the architecture of this tomb and the plenty of the decorations made this as one of the seven wonders of the ancient world. Since then any monumental tomb was called as 'mausoleum' when had monumental characteristics. But the mausoleum was a typical monument of the Classic age and it should not be correct to name structures built after the end of the Paganism. Mausolus' tomb, according to a reconstruction by Krischen, had a grat basament 22 meters tall, sourronded in the lower part by steps where a columnade of nine columns times eleven (these columns being thirteen meters high). Above this columnade a great pyramid 7 metres high and a statue of a four horses chariot. The whole tomb was 49 meters high.
For the Signa Romanorum list only those mausoleums having at least one measure greater then the dimensions of a famous tomb were  included. These dimensions being the ones of the Cecilia Metella's tomb on the ancient Appian Way, having a drum height of 11 meters and a diameter of 29,50 mt.

Structural and architectural elements:

Mausoleums have several different shapes with not a general rule. Generally they looks like a cylinder, often on a squared or rectangular base. All of them were built for commemorial purpose.