Wales international Bale, 31, is expected to rejoin Spurs on loan.
He flew into Luton Airport on Friday before travelling to the training ground in Enfield, North London.
Bale originally joined Spurs from Southampton in 2007 before moving to the Spanish giants for a then world record £85m in 2013.
He has gone on to score more than 100 goals for Real and won four Champions Leagues.
It is also anticipated Real Madrid full-back Sergio Reguilon will complete his transfer to Tottenham on Friday. The 23-year-old Spain international played last season on loan at Sevilla, winning the Europa League.