Part 1 of the 100^th episode of hit FOX musical comedy-drama Glee aired March 18.

The milestone episode featured Gwyneth Paltrow as Holly Holiday and Kristen Chenoweth as April Rhodes, who joined the original cast of Glee to perform a number of favorite songs to save the singing club. Original cast members also include Heather Morris (Brittany), Harry Shum Jr. (Mike), Mark Salling (Puck), Amber Riley (Mercedes) and Dianna Agron as Quinn.

The episode also featured a tribute to late actor Cory Monteith, whose character Finn was mentioned.

The second part of Glee's 100^th episode will air March 25 at 8 p.m. on FOX.

Glee's album to celebrate its 100^th episode titled "Glee: The Music Celebrating 100 Episodes" will be released on March 25, 2014.

See the full tracklist for the album below:

1. "Keep Holding On"* featuring Mark Salling (Puck)

2. "Valerie"* featuring Naya Rivera (Santana) and Morris (Brittany)

3. "Defying Gravity"* featuring Lea Michele (Rachel), Chris Colfer (Kurt) and Riley (Mercedes)

4. "Raise Your Glass"* featuring Morrison (Will) and Chenoweth (April)

5. "Toxic"* featuring Rivera (Santana), Morris (Brittany) and Agron (Quinn)

6. "Happy" featuring Paltrow (Holly), Chenoweth (April), Morrison (Will), Darren Criss (Blaine) and Riley (Mercedes)

7. "Party All the Time" featuring Paltrow (Holly)

8. "Total Eclipse of the Heart"* featuring Morrison (Will) and Chenoweth (April)

9. "Loser Like Me"* featuring Criss (Blaine), Kevin McHale (Artie), Chord Overstreet (Sam) and Jenna Ushkowitz (Tina)

10. "Be Okay" featuring Michele (Rachel) and Rivera (Santana)

11. "I Am Changing" featuring Riley (Mercedes) and Colfer (Kurt)

12. "Just Give Me a Reason" featuring Agron (Quinn) and Salling (Puck)

13. "Don't Stop Believin'"* featuring Michele (Rachel), Criss (Blaine), Colfer (Kurt), Morrison (Will), McHale (Artie) and Ushkowitz (Tina)