Charles Ellicott Commentary 2 Chronicles 1:2-6

"And Solomon spake unto all Israel, to the captains of thousands and of hundreds, and to the judges, and to every prince in all Israel, the heads of the fathers` [houses]. So Solomon, and all the assembly with him, went to the high place that was at Gibeon; for there was the tent of meeting of God, which Moses the servant of Jehovah had made in the wilderness. But the ark of God had David brought up from Kiriath-jearim to [the place] that David had prepared for it; for he had pitched a tent for it at Jerusalem. Moreover the brazen altar, that Bezalel the son of Uri, the son of Hur, had made, was there before the tabernacle of Jehovah: and Solomon and the assembly sought unto it. And Solomon went up thither to the brazen altar before Jehovah, which was at the tent of meeting, and offered a thousand burnt-offerings upon it." — 2 Chronicles 1:2-6 (ASV)

Solomon and the national assembly go to the Mosaic tabernacle at Gibeon, and sacrifice upon the great altar of burnt offering. (Compare to 1 Kings 3:4, which the present section supplements and explains.)