Dedicated to the Lord Jesus Christ Who loved us, gave Himself for us, and washed us from our sins in His own Blood; and to the Church, which is His body.

The veil spoken of in Luke 23:45 reached from the ceiling to the floor, from wall to wall, and separated the Holy of Holies from the holy place in the temple. 
Solomon's temple was 30 cubits high (1 Kings 6:2), but Herod increased the height to 40 cubits according to the writings of Josephus, a first century historian. Depending on what standard we use to convert cubits to feet (there is uncertainty as to exactly what a cubit equaled in our feet and inches), this veil was somewhere between 60 feet and 90 feet high.
It is important that this veil was rent from top to bottom (Matthew 27:51; Mark 15:38). No man could have torn the veil this way. It was definitely God that ripped the veil. The time when this veil was torn corresponds exactly with the moment Jesus died.
Hebrews 9:1-9 tells us that the veil separated the Holy of Holies, where God dwelt, from the rest of the temple, where men dwelt. This signified that man was separated from God by sin (Isaiah 59:1-2). 
Only the high priest was permitted to pass beyond this veil, and only once each year (Exodus 30:10; Hebrews 9:7). This symbolized Christ who would enter into God's presence for us and make an atonement.
The moment that Christ died, the veil was torn in two, revealing that the sacrifice had been made and that there is no longer any separation between God and man. Jesus tore the veil, that is to say His flesh (Hebrews 10:20), in two and opened up a new way unto God through Himself.