Otto III van Holland
Otto van Holland (died 27 March 1249) was a bishop of Utrecht from 1233 to 1249.
Otto was the second son of William I, Count of Holland and his first wife Adelaide of Guelders.
He was elected as bishop in 1233, but because of resistance from the canons of Utrecht, his consecration was delayed until 1245.
He emerged as a forceful ruler who involved himself primarily in secular affairs.
After the death of his brother Floris IV, Count of Holland in 1234, he became guardian of Floris' son William II, Count of Holland, and he governed the County of Holland.
He resolved the problems in Drenthe, problems which had cost his predecessor Otto II of Lippe his life.
He also subjected the lords of Goor to his authority.
Bernhard VI, Prince of Anhalt-Bernburg
Bernhard VI, Prince of Anhalt- Bernburg( died 2 February 1468) was a German prince of the House of Ascania and ruler of the Principality of Anhalt- Bernburg.
He was the eldest son of Otto III, Prince of Anhalt- Bernburg, by his first unknown wife.
Otto III, Count of Rietberg
Count Otto III Rietberg (between 1475 and 1485 – 18 December 1535) was Count of Rietberg from 1516 to 1535.
Otto III was probably born between 1475 and 1485 as the eldest son of John I and his wife Margaret of Lippe.
Otto's second wife, Onna of Esens, introduced the Reformation in the County of Rietberg.
In 1533, Otto III appointed two preachers from Lippe, to teach the new faith in the parishes of Rietberg and Neuenkirchen.
Otto III suffered from ulcers on his leg.
He died on 18 December 1535 and was buried in the Marienfeld Abbey.
He was the last Count of Rietberg to be buried there.
On his gravestone in the cloister before the winter refectory a Latin text could be read:
Beside it was the grave stone of his first wife:
Leo of Vercelli
Leo ("c".965–1026) was a German prelate who served as the Bishop of Vercelli from 999.
Born in Hildesheim, he was made an archdeacon by 998 and was appointed to the see of Vercelli as the candidate of the Emperor Otto III and Pope Sylvester II following the assassination of Bishop Peter.
He worked tirelessly for the extension of imperial authority in Italy during the reigns of Otto III, Henry II and Conrad II.
He worked for the imperial chancery, receiving the high rank and title of logothete.
Only a few of Leo's writings have survived, and only one of his epistles.
A notable Latin verse encomium written at Rome praises Otto III and Pope Gregory V. He also left behind an elegy of his diocesan predecessor and the so-called "Metrum leonis", a sometimes-rhyming adonic poem with fabulous and personal elements.
Adelaide of Guelders
Adelaide of Guelders (– 1218) was the daughter of Count Otto I of Guelders and his wife, Richardis, the daughter of Duke Otto I of Bavaria and Agnes of Loon.
Also known as Adelaide of Bellich or Alice of Guelders.
In 1197 in Stavoren, she married Count William I of Holland.
They had five children:
Adelaide died in 1218, while her husband was away on the Fifth Crusade.
She was buried in Rijnsburg Abbey.
Louis the Junker
Louis the Junker of Hesse( 1305 – 2 February 1345) was a German nobleman.
He was the third son of Landgrave Otto I of Hesse and his wife Adelheid, a daughter of Otto III of Ravensberg.
Otto III, Holy Roman Emperor
Otto III( June/ July 980 – 23 January 1002) was Holy Roman Emperor from 996 until his early death in 1002.
A member of the Ottonian dynasty, Otto III was the only son of the Emperor Otto II and his wife Theophanu.
Otto III was crowned as King of Germany in 983 at the age of three, shortly after his father's death in Southern Italy while campaigning against the Byzantine Empire and the Emirate of Sicily.
Though the nominal ruler of Germany, Otto III's minor status ensured his various regents held power over the Empire.
His cousin Henry II, Duke of Bavaria, initially claimed regency over the young king and attempted to seize the throne for himself in 984.
When his rebellion failed to gain the support of Germany's aristocracy, Henry II was forced to abandon his claims to the throne and to allow Otto III's mother Theophanu to serve as regent until her death in 991.
Otto III was then still a child, so his grandmother, Adelaide of Italy, served as regent until 994.
In 996, Otto III marched to Italy to claim the titles of King of Italy and Holy Roman Emperor, which had been left unclaimed since the death of Otto II in 983.
Otto III also sought to reestablish Imperial control over the city of Rome, which had revolted under the leadership of Crescentius II, and through it the papacy.
Crowned as Emperor, Otto III put down the Roman rebellion and installed his cousin as Pope Gregory V, the first Pope of German descent.
After the Emperor had pardoned him and left the city, Crescentius II again rebelled, deposing Gregory V and installing John XVI as Pope.
Otto III returned to the city in 998, reinstalled Gregory V, and executed both Crescentius II and John XVI.
When Gregory V died in 999, Otto III installed Sylvester II as the new Pope.
Otto III's actions throughout his life further strengthened imperial control over the Catholic Church.
From the beginning of his reign, Otto III faced opposition from the Slavs along the eastern frontier.
Following the death of his father in 983, the Slavs rebelled against imperial control, forcing the Empire to abandon its territories east of the Elbe river.
Otto III fought to regain the Empire's lost territories throughout his reign with only limited success.
While in the east, Otto III strengthened the Empire's relations with Poland, Bohemia, and Hungary.
Through his affairs in Eastern Europe in 1000, he was able to extend the influence of Christianity by supporting mission work in Poland and through the crowning of Stephen I as the first Christian king of Hungary.
Returning to Rome in 1001, Otto faced a rebellion by the Roman aristocracy, which forced him to flee the city.
While marching to reclaim the city in 1002, Otto suffered a sudden fever and died in Castle Paterno in Faleria at the age of 21.
With no clear heir to succeed him, his early death threw the Empire into political crisis.
Emperor Daigo
Daigo's reign spanned the years from 897 through 930.
He is named after his place of burial.
Otto IV, Prince of Anhalt-Bernburg
Otto IV, Prince of Anhalt- Bernburg( died 1 May 1415) was a German prince of the House of Ascania and ruler of the principality of Anhalt- Bernburg.
He was the youngest son of Otto III, Prince of Anhalt- Bernburg, by his unknown first wife.
Gregor von Burtscheid
Gregor von Burtscheid( c. 940- 4 November 999), also known as Gregor von Calabria or Gregory of Cassano, was the first abbot of the Burtscheid Abbey, founded on order of Otto III, Emperor of the Holy Roman Empire.

Question: Where was the place of burial of Otto Iii Van Holland's mother?
Answer: Rijnsburg Abbey