Based on this verse -
45 Then, in the hearing of all the people, He said to His disciples,
Through this verse -
And in the daytime He was teaching in the temple, but at night He went out and stayed on the mountain called Olivet.
As well as the opening verses of Luke 21, especially without the phrase that we see in Matthew and Mark which says, as He sat on the Mount of Olives, the disciples came to Him privately, it is clear Jesus was in the Temple area and speaking in the hearing of the people as well as His disciples in Luke 21.
Witness #1 - Then, in the hearing of all the people, He said to His disciples,
Witness #2 - Then opening verses of Luke 21 - 1 And He looked up and saw the rich putting their gifts into the treasury, 2 and He saw also a certain poor widow putting in two mites. 3 So He said, "Truly I say to you that this poor widow has put in more than all; 4 for all these out of their abundance have put in offerings for God, but she out of her poverty put in all the livelihood that she had." 5 Then, as some spoke of the temple, how it was adorned with beautiful stones and donations, He said, 6 "These things which you see--the days will come in which not one stone shall be left upon another that shall not be thrown down."
Witness #3 - And in the daytime He was teaching in the temple, but at night He went out and stayed on the mountain called Olivet.
JLB