Model shrines have been uncovered in numerous excavations of biblical cities, but they are common throughout the Ancient Near East. Ziony Zevit says,
Some model shrines were found to contain built-in images of deities while others were empty. In the latter case, some scholars assume that a small portable image was placed inside when the shrine was in use. (The Religions of Ancient Israel, 328).
The model shrines come in a variety of sizes. Here is one excavated at Tell el-Farah, the biblical site of Tirzah.
Tirzah served as the capital of the northern kingdom of Israel during the reigns of Baasha (1 Kings 15:21) Elah and Zimri (1 Kings 16:17-18). Omri reigned six years in Tirzah before he purchased the hill of Samaria and moved the capital of Israel there (1 Kings 16:24).
The shrine discovered at Ashkelon is significant because it included a silver plated bull. See a low quality photo here.
Luke Chandler reports on the 2010 discovery of a shrine at Khirbet Qeiyafa, and includes two nice photos here.