The shofar is one of the world's oldest musical instruments. It is a ram's horn blown from which building on Holy days?

A shofar is an ancient musical horn made of ram's horn, used for Jewish religious purposes. Like the modern bugle, the shofar lacks pitch-altering devices. All pitch control is done by varying the player's embouchure. The shofar is blown in synagogue services on Rosh Hashanah and at the very end of Yom Kippur, and is also blown every weekday morning in the month of Elul running up to Rosh Hashanah. Shofars come in a variety of sizes and shapes, depending on the choice of animal and level of finish.

The shofar is mentioned frequently in the Hebrew Bible, the Talmud and rabbinic literature. The blast of a shofar emanating from the thick cloud on Mount Sinai made the Israelites tremble in awe (Exodus 19:16).

The shofar was used to announce holidays and the Jubilee year. The first day of the seventh month (Tishrei) is termed "a memorial of blowing", or "a day of blowing", the shofar. They were used for signifying the start of a war. Later, it was also employed in processions, as musical accompaniment and eventually it was inserted into the temple orchestra by David.