I read the following comment on a travel site:
Petra’s greatest asset – and also its worst asset – is its world-famous entrance.
If you have ever watched the movie Indiana Jones and the Last Crusade, you will remember the spectacular approach to the mysterious city carved in stone where Indy finds the Holy Grail.

The entrance to the ancient city of Petra in Jordan is the Siq, a narrow sandstone gorge nearly a mile long.
Not a movie set, the location shown in the movie and referred to in the quotation above is Petra, an ancient site in Jordan. The approach to the city is by way of a narrow sandstone gorge called the Siq.
The word asset, like the word liability has a specific legal meaning related to financial obligations. For example, a company is liable or responsible for all debts incurred as part of doing business. The debts are liabilities. Assets are things a company or an individual owns outright. If your car is paid for, it’s an asset. If you owe money on it, the remaining debt is a liability.
Both words have figurative meanings. An asset is an advantage. A liability is a disadvantage.
Because in the figurative sense assets are good things, to talk about Petra’s “worst asset” is to talk nonsense.
Better use of English to say:
Petra’s greatest asset – and its worst liability – is its world-famous entrance.

