It's said this was the case for the Taj Mahal. I'm reading Game of Thrones by George RR Martin right now and find a character in the story might have been guilty of this also. But was it proven to ever be done by an actual ruler or such?
From Jordanes, the 6th century author of De Origine Actibusque Getarum (The Origins and Acts of the Goths), we have a story of the famous death and burial of Alaric, King of the Visigoths and who is best known for his sack of Rome in 410.
After the sack of Rome, the Visigoths under Alaric set upon other parts of the Italian peninsula. Having gained the 'wealth of the Italians' it was Alaric's intention to cross to Africa via Sicily, however several ships were sunk in the attempt. According to Jordanes:
Alaric was cast down by the reverse, and while deliberating what he should do, was suddenly overtaken by an untimely death and departed from human cares. His people mourned for him with the uttermost affection. Then turning from its course the river Busentus [..] they lead a band of captives into the midst of its bed to dig out a place for his grave. In the depths of this pit they buried Alaric, together with many treasures, and then turned the waters back into their channel. And that none might ever know the place, they put to death all the diggers.
Another example is the first emperor of the Qin dynasty, Shi Huang, to whom a mountainside tomb was built. He is known chiefly for his unification of China using extreme and harsh legalist policies throughout his newly formed empire. His son, referred to as the "Second Emperor", completed the tomb upon the rulers death.
Below is the description of the fate of many individuals associated with the tomb:
After the interment had been completed, someone pointed out that the artisans and craftsmen who had built the tomb knew what was buried there, and if they should leak word of the treasures, it would be a serious affair. Therefore, after the articles had been placed in the tomb, the inner gate was closed off and the outer gate lowered, so that all the artisans and craftsmen were shut in the tomb and were unable to get out. Trees and bushes were planted to give the appearance of a mountain.
Quoted from SHI JI 6: THE BASIC ANNALS OF THE FIRST EMPEROR OF THE QIN, a record of the Qin dynasty written chiefly by Sima Qian
Since you asked about Taj Mahal- After the cometion of Taj, Shah Jahan (The Mughal Emperor who built the Taj), ordered to have the hands of all the workers cut off so that nobody else could replicate the Taj