"As so often happens in Israel, so it happened in 2003 when the Israel Railway Authority was constructing a rail connection between Ashdod and Ashkelon, those ancient Philistine, now modern cities on the Mediterranean coast: Ancient remains were discovered, work stopped, and the Israel Antiquities Authority was called in to investigate and excavate. What was unusual this time, however, was that the excavators came upon a massive hitherto-unknown neo-Assyrian palace dating to the late eighth century B.C.E." Source: Biblical Archaeology Society (2007)
"This is especially tantalizing because it will take a major excavation to fully excavate the palace. So far only a small portion of the building has been excavated. And for the time being, it has been covered back up—simply to protect it. Many senior archaeologists would love to undertake an expedition to expose the palace more fully, but it’s the same old problem: money (or lack thereof)."
Further excavations have been carried out over the years. In 2013, Tel Aviv University reported that "the heart of the well-preserved fortifications is a mud-brick wall up to more than 12 feet wide and 15 feet high. The wall is covered in layers of mud and sand that stretch for hundreds of feet on either side. When they were built in the eighth century B.C.E., the fortifications formed a daunting crescent-shaped defense for an inland area covering more than 17 acres."
Note: Judah and Israel were apparently separate kingdoms at the time of the neo-Assyrian invasion of Israel. Judah and Israel were at war and the king of Judah asked the Assyrians for help in his fight against Israel. Appealing to foreign armies for assistance like this is a risky business because your new allies don't always want to leave again.
According to Wikipedia, "in 738 BC, during the reign of king Menahem of Israel, Tiglath-Pileser III occupied Philistia (modern-day southwestern Israel and the Gaza Strip) and invaded Israel, imposing on it a heavy tribute. Ahaz, king of Judah, engaged in a war against Israel and Aramea, appealed for help to the Assyrian king by means of presents of gold and silver; Tiglath-Pileser III accordingly 'marched against Damascus, defeated and put king Rezin to death, and besieged the city itself'. Leaving part of his army to continue the siege, he advanced, ravaging with fire and sword the provinces east of the Jordan (Nabatea, Moab and Edom), Philistia, and Samaria [capitol city of Israel?]; and in 732 BC he took the chief Aramean state of Damascus, deporting many of its inhabitants and the Israelite inhabitants of Samaria to Assyria."