palaces - most applicable to Jerusalem (see on Isa 32:13).
multitude ... left - the noisy din of the city, that is, the city with its noisy multitude shall lie forsaken [Maurer].
forts - rather, “Ophel” (that is, the mound), the term applied specially to the declivity on the east of Zion, surrounded with its own wall (2Ch 27:3; 2Ch 33:14; 2Ki 5:24), and furnished with “towers” (or watchtowers), perhaps referred to here (Neh 3:26, Neh 3:27).
for ever - limited by thee, “until,” etc., Isa 32:15, for a long time.