Hecatomnus had been ambitious and had taken control of several of the neighboring cities and districts. Mausolus extended the territory even further so that it finally included most of southwestern Asia Minor.
Halicarnassus lived its brightest years during the reign of Mausolus During his reign Mausolus transferred his capital from Mylasa to Halicarnassus. Until then Halicarnassus was a comparatively small city, but Mausolus, observing her natural advantages for fortification and commerce from sea. His ideas were never on a niggardly scale, and he set out to create a worthy capital city.
After several rulers of Hekatomnos Dynasty, in 377 BC, King Mausolos started ruling Caria.
He transplanted the inhabitants of six of the eight Lelegian cities from the surrounding area, the peninsula. These were of varying size, but some at least, if we may judge by the tribute they paid to Athens in the fifth century, seem to have been comparable to Halicarnassus herself, and the population of the new city must have been four or five times that of the old. Mausolos and his queen Artemisia ruled halikarnassus for 24 years
Then in 353 BC. Mausolus died, leaving his queen Artemisia, who was also his sister (It was the custom in Caria for rulers to marry their own sisters), broken-hearted. It is not certain that Mausolos initiated the construction of the monument of moussoleion later, but as a tribute to him, Artemisia decided to build him the most splendid tomb in the known world. It became a structure so famous that it was called one of the Seven Wonders of the world. Mausolus’s name is now associated with all stately tombs through our modern word
The sculptures include massive figures identified as Mausolos & Artemisia themselves, though it seems these are only the best preserved of a whole series of statues as many fragments of similarly huge figures have been found. Several sections of frieze and a sequence of lion statues ( originally nearly fifty, the three best preserved on display in London, another is in Istanbul). Conjecture surrounds the exact placing of all these sculptures on the monument, except for the largest of all, an enormous horse, originally one of four from the chariot group at the summit of the monument.