Question: When did construction begin on the stadium that hosted the K-1 World Grand Prix 2003 Final?

Context paragraphs:
K-1 World Grand Prix 2003 Final Elimination: K-1 World Grand Prix 2003 Final Elimination was a kickboxing event promoted by the K-1 organization.  The event was held at the Osaka Dome in Osaka, Japan on Saturday, October 11, 2003 in front of 31,700 spectators.  It was the final elimination competition for the K-1 World Grand Prix 2003, involving fourteen fighters from across the world, with all bouts being fought under K-1 Rules (100 kg/156-220 lbs).  The fourteen fighters were a mixture of invitees or had qualified via previous events (for more information on this see the bulleted list below).

K-1 Grand Prix '98 Final Round: K-1 Grand Prix '98 Final Round was a martial arts event promoted by the K-1.  The event was held at the Tokyo Dome in Tokyo, Japan on Sunday, December 13, 1998 in front of 63,800 spectators.  It was the sixth K-1 World Grand Prix final involving eight of the world's best heavyweight fighters (+95 kg/209 lbs), with all bouts fought under K-1 Rules.  The eight finalists had all qualified via elimination fights at the K-1 World Grand Prix '98 Opening Round.  Also on the card was a number of 'Freshman Fights' fought under a mixture of Jiu-Jitsu Freestyle and K-1 Rules (various weight classes).  In total there were eighteen fighters at the event, representing seven countries.

K-1 World Grand Prix 2003 Final: K-1 World Grand Prix 2003 Final was a kickboxing event promoted by the K-1 organization.  The event was held at the Tokyo Dome in Tokyo, Japan on Saturday,December 6, 2003 in front of 67,320 spectators.  It was the eleventh K-1 World Grand Prix final involving ten of the world's best fighters (two being reservists).  The eight finalists had almost all qualified via preliminary events, while two additional fighters were invited as reserve fighters (for more detail on this see bulleted list below), with all bouts being fought under K-1 Rules (100 kg/156-220 lbs).  As well as tournament bouts there was also an 'Opening Fight' between Yusuke Fujimoto and Matthias Riccio and a 'Super Fight' between Martin Holm and Jan Nortje, both fought under K-1 Rules.  In total there were fourteen fighters at the event, representing ten countries.

K-1 World Grand Prix 2004 Final: K-1 World Grand Prix 2004 Final was a kickboxing event promoted by the K-1 organization.  It was the twelfth K-1 World Grand Prix final, involving twelve of the world's best K-1 fighters (four being reservists) from eight countries, with all bouts fought under K-1 Rules (100 kg/156-220 lbs).  The tournament qualifiers had almost all qualified via the K-1 World Grand Prix 2004 Final Elimination with the exception of Remy Bonjasky who was the reigning champion.

K-1 World Grand Prix 2006 in Tokyo Final: K-1 World Grand Prix 2006 in Tokyo Final was a kickboxing promoted by the K-1 organization.  It was the fourteenth K-1 World Grand Prix final, the culmination of a year full of regional elimination tournaments, involving twelve of the world's best K-1 fighters (four being reservists).  It followed K-1's classic tournament format - eight fighters compete in a quarter final contests with the four winners advancing to a pair of semi final bouts, and the two winners there clashing in the final.  All fights were conducted under K-1 Rules (100 kg/156-220 lbs), three rounds of three minutes each, with a possible tiebreaker.

K-1 Grand Prix '99 Final Round: K-1 Grand Prix '99 Final Round was a martial arts event promoted by the K-1 organization.  It was the seventh K-1 World Grand Prix final involving eight of the world's best fighters, with all bouts fought under K-1 Rules.  The eight finalists had all qualified via elimination fights at the K-1 World Grand Prix '99 Opening Round.  Also on the card was a number of 'Freshman Fights' and an 'Opening Fight' fought under a mixture of Jiu-Jitsu and K-1 Rules (various weight class) and two 'Super Fights' fought under K-1 Rules (various weight classes).  In total there were twenty fighters at the event, representing eight countries.

K-1 World Grand Prix 2008 Final: K-1 World Grand Prix 2008 Final was a martial arts event held by the K-1 on Saturday December 6, 2008 at the Yokohama Arena in Yokohama, Japan.  It was the 16th K-1 World GP Final, the culmination of a year full of regional elimination tournaments.  All fights followed the classic 8-man tournament format and were conducted under K-1 rules; three rounds of three minutes each, with a possible tiebreaker.  The qualification for the top eight fighters in this event was held at K-1 World Grand Prix 2008 in Seoul Final 16.

Tokyo Dome: Tokyo Dome (東京ドーム , Tōkyō Dōmu ) is a stadium in Bunkyo, Tokyo, Japan.  Construction on the stadium began on May 16, 1985, and it opened on March 17, 1988.  It was built on the site of the Velodrome, adjacent to the predecessor ballpark, Kōrakuen Stadium.  It has a maximum total capacity of 55,000 depending on configuration, with an all-seating configuration of 42,000.

K-1 World Grand Prix 2005 in Tokyo Final: K-1 World Grand Prix 2005 in Tokyo Final was a kickboxing event promoted by the K-1.  The event was held at the Tokyo Dome in Tokyo, Japan on Saturday, November 19, 2005 in front of 58,213 spectators.  It was the thirteenth K-1 World Grand Prix final, involving twelve of the world's best K-1 fighters (four being reservists), with all bouts fought under K-1 Rules (100 kg/156-220 lbs).  The tournament qualifiers had almost all qualified via the K-1 World Grand Prix 2005 in Osaka - Final Elimination with the exception of Remy Bonjasky who was the reigning champion.  As well as tournament matches there was also an 'Opening Fight' fought under K-1 Rules between Patrick Barry and Alexander Pitchkounov.  In total there were fourteen fighters at the event, representing eleven countries.

K-1 World Grand Prix 2010 Final: K-1 World Grand Prix 2010 Final was a martial arts event that was held by the K-1 on Saturday, December 11, 2010.  It was the 18th K-1 World GP Final, the culmination of a year full of regional elimination tournaments.  All fights followed K-1's classic tournament format and was conducted under K-1 Rules, three rounds of three minutes each, with a possible tiebreaker.  The qualification for the top eight fighters was held at the K-1 World Grand Prix 2010 in Seoul Final 16 on October 2, 2010 in Seoul, Korea.

Supporting paragraphs: K-1 World Grand Prix 2003 Final Tokyo Dome
Answer: May 16, 1985