The Tomb of Sultan Ahmed I is at the northern corner of the Blue Mosque complex, on the Sultanahmet Square side. Ahmed I commissioned the mosque and was buried here in 1617.
Practical details: entry is free, the visit takes about ten minutes, and the building is closed on Mondays. Shoes are removed at the door and women should cover their heads, as in a mosque. Photography without flash is permitted.
Six sarcophagi stand inside, including those of Ahmed I, his consort Kosem Sultan, and sultans Osman II and Murad IV. The Iznik tilework dates from the same years as the mosque itself.
From Hotel Yasmak Sultan it is about ten minutes on foot, and it takes almost no extra time if you are already visiting the mosque.