Why is the US building a billion-dollar massive embassy in Beirut, Lebanon?

The US is building a $1 billion embassy in Beirut, Lebanon, which will be the second largest in the world after Iraq. Questions about the embassy are already being raised.
Located in the suburb of Awkar, about 10 miles from the center of Beirut, it was built adjacent to the site of the current embassy. Under construction since 2017, this complex looks like its own city. the complex is larger than any government facility in Lebanon.
Former British Ambassador to Uzbekistan Craig Murray emphasized that this is not an embassy but something 50 times bigger.
Why would they spend a billion dollars of taxpayers’ money on an embassy in a country with about 86,000 American citizens? Is this really an embassy, or a bastion for covert operations in West Asia?